CoCreateGuid

C# Signature:

[DllImport("ole32.dll", ExactSpelling=true, PreserveSig=false)]
static extern int CoCreateGuid ( out Guid guid );

Sample Code:

Guid guid;
CoCreateGuid ( out guid );
string guid_s = guid.ToString();
// or:
Marshal.ThrowExceptionForHR ( CoCreateGuid ( out guid ) , new IntPtr ( -1 ) );
guid_s = guid.ToString();

Alternative Managed API:

System.Guid.NewGuid()