Four chinchillas were trained to lick a drinking tube located in one end of a double-grille cage to obtain their daily ration of water. When the licking rate stabilized (4-5 licks /sec) in daily sessions of about 20 min, avoidance conditioning began. The animal was required to leave the tube and cross a midline barrier to avoid shock when one sound, the positive conditioned stimulus (+CS), was presented, while he could continue licking without threat of shock when another sound, the negative conditioned stimulus (—CS), was presented. The chinchillas quickly learned a near perfect association of crossing the barrier to +CS and not crossing to — CS, which was maintained throughout the 30 daily sessions of the experiment. Intertrial crossings were virtually absent and licking rates provided a sensitive, additional measure of an animal's response to the stimuli.