I don't see why not. It depends on the width of the snake too. If the rat is more than 1-11/2 times the width, I'd go one size smaller. I actually used the snake measurer program to measure the width of one of the medium mice, and my snake to see how big it was compared to her. It was within the limits, but she seemed to really work to eat it, so I went back down in size and just fed her an extra hopper.