Two experiments investigated the effects of lithium chloride on activity and rectal temperature in rats. Lithium injections, relative to saline injections in controls, caused decreases in both activity and temperature. Importantly, lithium’s effects did not diminish over the course of eight repeated injections, although preexposure to lithium did attenuate its conditioning effectiveness in a flavor-conditioning trial. The results support the idea that drug tolerance is not of great importance in the lithium-mediated US-preexposure effect in flavor conditioning.