Rats do not serve any purpose in the game and exist only to add an aspect of realism. They can be killed in one hit with any firearm in the game. They are mainly found near tramps under freeways and in abandoned places such as sewers. Rats can also be found scurrying around Sandy Shores and in Trevor's dirty trailer.
Rats do not have aggressive behavior and will run if approached by the player.
- Rats also appeared in Rockstar Games' Bully.
- The player can't play as a Rat after eating a Peyote Plant, just like the Blue Whale.