C# Signature:

[DllImport("coredll.dll")]
public static extern int RegCreateKeyEx(
   UIntPtr hKey, string lpSubKey, uint dwReserved, string lpClass,
   uint dwOptions, int samDesired, IntPtr lpSecurityAttributes,
   out IntPtr phkResult, out RegistryDispositionValue lpdwDisposition);

User-Defined Types:

enum RegistryDispositionValue : uint
{
   REG_CREATED_NEW_KEY     = 0x00000001,
   REG_OPENED_EXISTING_KEY = 0x00000002
}

Notes:

The .NET Compact Framework does not contain a HandleRef type, so it may be necessary to call GC.KeepAlive after calling this function if the calling class wraps the hKey parameter as an unmanaged resource.

Tips & Tricks:

C#:

public UIntPtr HKEY_CLASSES_ROOT = (UIntPtr)0x80000000;

public const int REG_OPTION_NON_VOLATILE = 0;

:::

int iResult;

IntPtr ipKey = IntPtr.Zero;

string strRegKeyPath;

int iDisposition;

iResult = RegCreateKeyEx(HKEY_CLASSES_ROOT, strRegKeyPath, 0,

   null, REG_OPTION_NON_VOLATILE, 0, IntPtr.Zero, out ipKey,
   out iDisposition);

Alternative Managed API:

CF V2.0

Microsoft.Win32.Registry.LocalMachine.CreateSubKey(SubKey as string)