RegistryKey Class

Represents a key-level node in the Windows registry. This class is a registry encapsulation.

Namespace: Microsoft.Win32
Assembly: mscorlib (in mscorlib.dll)

public sealed class RegistryKey : MarshalByRefObject, IDisposable
/** @attribute ComVisibleAttribute(true) */ 
public final class RegistryKey extends MarshalByRefObject implements IDisposable
public final class RegistryKey extends MarshalByRefObject implements IDisposable

To get an instance of RegistryKey, use the one of the static members of the Registry class.

The registry acts as a central repository of information for the operating system and the applications on a computer. The registry is organized in a hierarchical format, based on a logical ordering of the elements stored within it (please see Registry for the base-level items in this hierarchy). When storing information in the registry, select the appropriate location based on the type of information being stored. Be sure to avoid destroying information created by other applications, because this can cause those applications to exhibit unexpected behavior, and can also have an adverse effect upon your own application.

Registry keys are the base unit of organization in the registry, and can be compared to folders in Windows Explorer. A particular key can have subkeys, just as a folder can have subfolders. Each key can be deleted, as long as the user has the appropriate permissions to do so, and the key is not a base key or at the level directly under the base keys. Each key can also have multiple values associated with it (a value can be compared to a file), which are used to store the information — for example, information about an application installed on the computer. Each value holds one particular piece of information, which can be retrieved or updated when required. For instance, you can create a RegistryKey for your company, under the key HKEY_LOCAL_MACHINE\Software, and then a subkey for each application that your company creates. Each subkey holds the information specific to that application, such as color settings, screen location and size, or recognized file extensions.

Note that information stored in the registry is available to other applications and users, and therefore should not be used to store security data or critical application information.

Caution noteCaution

Do not expose RegistryKey objects in such a way that a malicious program could create thousands of meaningless subkeys or key/value pairs. For example, do not allow callers to enter arbitrary keys or values.

Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows CE Platform Note: In .NET Compact Framework applications, before deleting a subkey any open instances of the subkey and its child subkeys must be explicitly closed. The maximum depth of subkeys, as determined by Windows CE, is 15.

The following code example shows how to create a subkey under HKEY_CURRENT_USER, manipulate its contents, and then delete the subkey.

using System;
using System.Security.Permissions;
using Microsoft.Win32;

[assembly: RegistryPermissionAttribute(SecurityAction.RequestMinimum,
    ViewAndModify = "HKEY_CURRENT_USER")]

class RegKey
    static void Main()
        // Create a subkey named Test9999 under HKEY_CURRENT_USER.
        RegistryKey test9999 = 
        // Create two subkeys under HKEY_CURRENT_USER\Test9999. The
        // keys are disposed when execution exits the using statement.
            testName = test9999.CreateSubKey("TestName"),
            testSettings = test9999.CreateSubKey("TestSettings"))
            // Create data for the TestSettings subkey.
            testSettings.SetValue("Language", "French");
            testSettings.SetValue("Level", "Intermediate");
            testSettings.SetValue("ID", 123);

        // Print the information from the Test9999 subkey.
        Console.WriteLine("There are {0} subkeys under {1}.", 
            test9999.SubKeyCount.ToString(), test9999.Name);
        foreach(string subKeyName in test9999.GetSubKeyNames())
                tempKey = test9999.OpenSubKey(subKeyName))
                Console.WriteLine("\nThere are {0} values for {1}.", 
                    tempKey.ValueCount.ToString(), tempKey.Name);
                foreach(string valueName in tempKey.GetValueNames())
                    Console.WriteLine("{0,-8}: {1}", valueName, 

            testSettings = test9999.OpenSubKey("TestSettings", true))
            // Delete the ID value.

            // Verify the deletion.
                "id", "ID not found."));

        // Delete or close the new subkey.
        Console.Write("\nDelete newly created registry key? (Y/N) ");
        if(Char.ToUpper(Convert.ToChar(Console.Read())) == 'Y')
            Console.WriteLine("\nRegistry key {0} deleted.", 
            Console.WriteLine("\nRegistry key {0} closed.", 


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0