When Peter told Mary Jane originally, she revealed to him that she always knew. According to the 'Parallel Lives' Trade Paperback which tells the origins of both MJ and Peter, published in 1989, Mary Jane discovered Peter's secret identity the night of Uncle Ben's murder. Mary Jane was at her Aunt's next door to Aunt May and Uncle Ben's house. She had spied Peter before that day and thought of him as being rather cute (apparently she's always had a crush on him). The night that Uncle Ben was murdered by the burglar, Aunt May was brought next door to Mary Jane's Aunt Anna's house. They cared for May there while Mary Jane looked out the window to see Peter learning of Uncle Ben's death from the police. Next, she witnessed Peter go into his house and...SURPRISE!...Spider-man crawled out of Peter's window! Mary Jane wanted to chase him down, because in the previous weeks she had become infatuated with the mystery of Spider-man. Being that she already liked Peter and had a bit of a fangirl crush on Spider-man, she wanted to talk to him. However, Mary Jane decided that she would go out and party, something she frequently did instead. This caused her Mother and Aunt to become rather upset, and while Mary Jane was dancing the night away she kept trying to convince herself that she 'Didn't see what she saw'. Keep in mind, Mary Jane was not introduced into the Spider-man comics until 1966, 4 years after Spider-man's beginning. This story in 'Parallel Lives' is actually a way of diving deeper into both Mary Jane and Peter's back stories, filling in gaps and giving tidbits we never knew. Its a very interesting book that gives both Peter and MJ a deep characterization. I highly suggest picking it up. It is available through www.milehighcomics.com. Also keep in mind that once a different writer comes on to Spider-man, he may end up changing mythos and existing information...usually resulting in terrible storylines and lack of continuity. Case in point: Maximum Clonage (shudder) and the clone garbage in the mid 90's, and other recent stories..

Shed discovered this before peter went to fight doc oc