I need to create a new environment variable and update an existing one using a batch file. Any help will be highly appreciated.. Thanks and regards, Shane

In which environment?

windows XP and vista.

You can't use a batch script to modify persistently the Windows XP/Vista environment.

If you don't mind downloading something, use the program setx

It is possible to create or modify environment variables using reg.exe(available in most xp machines not so sure about vista), there is however a catch, the variables aren't loaded until the next reboot(or possibly if another program broadcasts a WM_SETTINGSCHANGE, even then it won't be available to existing shells and is highly unlikely). One of the keys is HKEY_CURRENT_USER\Environment or <userhive>\Environment All of the global variables seem to be accessable from: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment Values are the variable names and their data is what the variable expand to.