Microsoft.Win32.RegistryKey rk = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@ "SOFTWARE / Classes / MIME / Database / Content Type"); foreach (string s in rk.GetSubKeyNames ()) {textBox1.Text = s " / r / n ";} Finally, in my own machine output: application / cdfapplication / fractalsapplication / futuresplashapplication / htaapplication / mac-binhex40application / msaccessapplication / mswordapplication / pdfapplication / pkcs10application / pkcs7-mimeapplication / pkcs7-signatureapplication / pkix-certapplication / pkix- crlapplication / postscriptapplication / set-payment-initiationapplication / set-registration-initiationapplication / vnd.adobe.xfdfapplication / vnd.fdfapplication / vnd.ms-excelapplication / vnd.ms-pki.certstoreapplication / vnd.ms-pki.pkoapplication / vnd. ms-pki.seccatapplication / vnd.ms-pki.stlapplication / vnd.ms-powerpointapplication / vnd.rmfapplication / vnd.visioapplication / x-cdfapplication / x-complusapplication / x-compressapplication / x-compressedapplication / x-gzipapplication / x- Internet-SignuPability / X-iPhoneApplication / X-LatexApplica tion / x-mix-transferapplication / x-mplayer2application / x-ms-wmdapplication / x-ms-wmsapplication / x-ms-wmzapplication / x-msexcelapplication / x-mspowerpointapplication / x-pkcs12application / x-pkcs7-certificatesapplication / x- pkcs7-certreqrespapplication / x-shockwave-flashapplication / x-stuffitapplication / x-tarapplication / x-troff-manapplication / x-x509-ca-certapplication / x-zip-compressedapplication / xmlaudio / aiffaudio / basicaudio / midaudio / midiaudio / mp3audio / mpegaudio / mpegurlaudio / mpgaudio / wavaudio / x-aiffaudio / x-backgroundaudio / x-midaudio / x-midiaudio / x-mp3audio / x-mpegaudio / x-mpegurlaudio / x-mpgaudio / x-ms-waxaudio / x-ms- WMAAUDIO / X-WAVIMAGE / BMPIMAGE / GIFIMAGE / JPEGIMAGE / PJPEGIMAGE / PNGIMAGE / SVGIMAGE / SVG
