Body temperature (Tb) and drinking were measured for five days in male and female rats. On day 6 (S1) the rats were injected with saline. On day 7 (P1) they were injected with PCPA (300 mg/kg IP). Measurements continued for 12 days. Immediately after PCPA Tb dropped. After that, the amplitude of the daily Tb rhythm was significantly decreased from days P2-P5. Females were more affected than males. Nocturnality of drinking was decreased on days P2-P4. Because the peak of the Tb rhythm advanced after PCPA, while the peak of the drinking rhythm was delayed, we conclude that the attenuation of the Tb rhythm was a direct result of PCPA treatment rather than a masking effect due to the attenuation of other rhythms. Other rats were thermally challenged during the first week post-PCPA. There were no differences in ability to regulate Tb in the cold, and the small variations in the heat were overshadowed by gender differences.