oddly enough, i just did this yesterday. i opened a 126 cartridge and replaced it with 35mm. i'll put it on my blog sometime in the next few days. the film size is the same, but depending in the kind of camera, you probably have to trim the top sprockets off the film, as it interferes with the cocking mechanism on some cameras. if you have a really basic camera that just winds, you can leave it as is.