Stream.CanWrite Property tells whether the current stream supports writing.
Imports System Imports System.IO Class TestRW Public Shared Sub Main() Dim fs As New FileStream("MyFile.txt", FileMode.OpenOrCreate, _ FileAccess.Write) If fs.CanRead And fs.CanWrite Then Console.WriteLine("MyFile.txt can be both written to and read from.") Else If fs.CanWrite Then Console.WriteLine("MyFile.txt is writable.") End If End If End Sub End Class