Are you referring to the "Reason-Phrase"(http://www.w3.org/Protocols/rfc2616/rfc2616-sec6.html) ( If so, I've tried everything I can think of and have been unable to come up with a way to set that field. LV seems to default to using the ones defined by http. If you just want to send data back you can always just use "set response.vi". I just used that setting the header to 401 and writing a response string ("OH NO! ERROR!" in my case) and the browser correctly displayed that string despite the error code. Are you saying this didn't work for you?