I am trying to figure out where does the Windows registry store allcurrentlyCONNECTEDUSB devices.So, if I connect a USB device and I lookat that location in the registryI shouldsee new entry, and when I remove the the USB device, it is removed from that registry location.Thanks.

It's in HKLM\System\CurrentControlSet\Enum\USB ... but I don't think it gets removed when you remove the device. It should remember it - that's the point. What is it you're trying to accomplish?Lanwench [MVP - Exchange] ** Do not fold, spindle or mutilate. Fill in the box completely and erase any stray marks. Use only a #2 pencil.

If it is always there in the Registry, then how could my Windows application find out what USB devices are plugged in at any given time? I dont care about the installed but unplugged ones.

hi marzk,The answer to your question is Registry keys control how USB device drivers are loaded. so when a USB device is attached, there are multiple path where in these registry are referenced.Important path is HKLM\Drivers\USB\loadclients key.also a corresponding class id for every device you plug in and these gets registered under HKLM\system\currentcontrolset\control\class and the corresponding GUID , for USB falls under HID classandother devices fall into serial port devices / i8042 port devices etc..so if i dig in more it would be usbhub.sys which communicates to usbd.sys ( host controller class driver) --> uhcd.sys or openhci.sys drivers ( these are miniclass drivers ) please let us know if you need more info.sainath !analyze