diff --git a/csharp/src/Microsoft.ML.OnnxRuntime/InferenceSession.cs b/csharp/src/Microsoft.ML.OnnxRuntime/InferenceSession.cs
index 7964302956..77b5b4c624 100644
--- a/csharp/src/Microsoft.ML.OnnxRuntime/InferenceSession.cs
+++ b/csharp/src/Microsoft.ML.OnnxRuntime/InferenceSession.cs
@@ -46,6 +46,25 @@ namespace Microsoft.ML.OnnxRuntime
             Init(modelPath, options);
         }
 
+        /// <summary>
+        /// Constructs an InferenceSession from a model data in byte array
+        /// </summary>
+        /// <param name="model"></param>
+        public InferenceSession(byte[] model)
+        {
+            _builtInSessionOptions = new SessionOptions(); // need to be disposed
+            Init(model, _builtInSessionOptions);
+        }
+
+        /// <summary>
+        /// Constructs an InferenceSession from a model data in byte array, with some additional session options
+        /// </summary>
+        /// <param name="model"></param>
+        /// <param name="options"></param>
+        public InferenceSession(byte[] model, SessionOptions options)
+        {
+            Init(model, options);
+        }
 
         /// <summary>
         /// Meta data regarding the input nodes, keyed by input names
@@ -182,17 +201,39 @@ namespace Microsoft.ML.OnnxRuntime
 
         #region private methods
 
-        protected void Init(string modelPath, SessionOptions options)
+        private void Init(string modelPath, SessionOptions options)
         {
             var envHandle = OnnxRuntime.Handle;
+            var session = IntPtr.Zero;
 
-            _nativeHandle = IntPtr.Zero;
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                NativeApiStatus.VerifySuccess(NativeMethods.OrtCreateSession(envHandle, System.Text.Encoding.Unicode.GetBytes(modelPath), options.Handle, out session));
+            else
+                NativeApiStatus.VerifySuccess(NativeMethods.OrtCreateSession(envHandle, System.Text.Encoding.UTF8.GetBytes(modelPath), options.Handle, out session));
+
+            InitWithSessionHandle(session, options);
+        }
+
+        private void Init(byte[] modelData, SessionOptions options)
+        {
+            var envHandle = OnnxRuntime.Handle;
+            var session = IntPtr.Zero;
+
+            NativeApiStatus.VerifySuccess(NativeMethods.OrtCreateSessionFromArray(envHandle, modelData, (UIntPtr)modelData.Length, options.Handle, out session));
+
+            InitWithSessionHandle(session, options);
+        }
+
+        /// <summary>
+        /// Initializes the session object with a native session handle
+        /// </summary>
+        /// <param name="session">Handle of a native session object</param>
+        /// <param name="options">Session options</param>
+        private void InitWithSessionHandle(IntPtr session, SessionOptions options)
+        {
+            _nativeHandle = session;
             try
             {
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
-                    NativeApiStatus.VerifySuccess(NativeMethods.OrtCreateSession(envHandle, System.Text.Encoding.Unicode.GetBytes(modelPath), options.Handle, out _nativeHandle));
-                else
-                    NativeApiStatus.VerifySuccess(NativeMethods.OrtCreateSession(envHandle, System.Text.Encoding.UTF8.GetBytes(modelPath), options.Handle, out _nativeHandle));
 
                 // Initialize input/output metadata
                 _inputMetadata = new Dictionary<string, NodeMetadata>();
diff --git a/csharp/src/Microsoft.ML.OnnxRuntime/NativeMethods.cs b/csharp/src/Microsoft.ML.OnnxRuntime/NativeMethods.cs
index 8813011450..e3ccbb8844 100644
--- a/csharp/src/Microsoft.ML.OnnxRuntime/NativeMethods.cs
+++ b/csharp/src/Microsoft.ML.OnnxRuntime/NativeMethods.cs
@@ -137,6 +137,7 @@ namespace Microsoft.ML.OnnxRuntime
             OrtReleaseStatus = (DOrtReleaseStatus)Marshal.GetDelegateForFunctionPointer(api_.ReleaseStatus, typeof(DOrtReleaseStatus));
 
             OrtCreateSession = (DOrtCreateSession)Marshal.GetDelegateForFunctionPointer(api_.CreateSession, typeof(DOrtCreateSession));
+            OrtCreateSessionFromArray = (DOrtCreateSessionFromArray)Marshal.GetDelegateForFunctionPointer(api_.CreateSessionFromArray, typeof(DOrtCreateSessionFromArray));
             OrtRun = (DOrtRun)Marshal.GetDelegateForFunctionPointer(api_.Run, typeof(DOrtRun));
             OrtSessionGetInputCount = (DOrtSessionGetInputCount)Marshal.GetDelegateForFunctionPointer(api_.SessionGetInputCount, typeof(DOrtSessionGetInputCount));
             OrtSessionGetOutputCount = (DOrtSessionGetOutputCount)Marshal.GetDelegateForFunctionPointer(api_.SessionGetOutputCount, typeof(DOrtSessionGetOutputCount));
@@ -242,6 +243,14 @@ namespace Microsoft.ML.OnnxRuntime
                                                 out IntPtr /**/ session);
         public static DOrtCreateSession OrtCreateSession;
 
+        public delegate IntPtr /* OrtStatus* */DOrtCreateSessionFromArray(
+                                                IntPtr /* (OrtEnv*) */ environment,
+                                                byte[] modelData,
+                                                UIntPtr modelSize,
+                                                IntPtr /* (OrtSessionOptions*) */sessionOptions,
+                                                out IntPtr /**/ session);
+        public static DOrtCreateSessionFromArray OrtCreateSessionFromArray;
+
         public delegate IntPtr /*(ONNStatus*)*/ DOrtRun(
                                                 IntPtr /*(OrtSession*)*/ session,
                                                 IntPtr /*(OrtSessionRunOptions*)*/ runOptions,  // can be null to use the default options
diff --git a/csharp/test/Microsoft.ML.OnnxRuntime.Tests/InferenceTest.cs b/csharp/test/Microsoft.ML.OnnxRuntime.Tests/InferenceTest.cs
index bc3a34ad71..4257d5e2b1 100644
--- a/csharp/test/Microsoft.ML.OnnxRuntime.Tests/InferenceTest.cs
+++ b/csharp/test/Microsoft.ML.OnnxRuntime.Tests/InferenceTest.cs
@@ -792,6 +792,26 @@ namespace Microsoft.ML.OnnxRuntime.Tests
             }
         }
 
+        [Fact]
+        private void TestInferenceSessionWithByteArray()
+        {
+            // model takes 1x5 input of fixed type, echoes back
+            string modelPath = Path.Combine(Directory.GetCurrentDirectory(), "test_types_FLOAT.pb");
+            byte[] modelData = File.ReadAllBytes(modelPath);
+
+            using (var session = new InferenceSession(modelData))
+            {
+                var container = new List<NamedOnnxValue>();
+                var tensorIn = new DenseTensor<float>(new float[] { 1.0f, 2.0f, -3.0f, float.MinValue, float.MaxValue }, new int[] { 1, 5 });
+                var nov = NamedOnnxValue.CreateFromTensor("input", tensorIn);
+                container.Add(nov);
+                using (var res = session.Run(container))
+                {
+                    var tensorOut = res.First().AsTensor<float>();
+                    Assert.True(tensorOut.SequenceEqual(tensorIn));
+                }
+            }
+        }
 
         [DllImport("kernel32", SetLastError = true)]
         static extern IntPtr LoadLibrary(string lpFileName);