Previous work has shown that a single oral administration of atrazine (ATR), a chlorotriazine herbicide, causes rapid increases in plasma adrenocorticotropic hormone (ACTH), serum corticosterone (CORT) and progesterone. The mechanism for these effects is unknown. To test whether administration of ATR causes hypothalamic–pituitary–adrenal (HPA) axis activation through the production of a generalized stress response resulting from gastrointestinal distress, we conducted both conditioned taste avoidance (CTA) and pica behavior experiments. Body temperature data were also collected to detect the presence of stress-induced hyperthermia. Adult male Wistar rats were given a single oral dose of ATR (0, 5, 25, 50, 100, or 200mg/kg) or the primary ATR metabolite diamino-s-chlorotriazine (DACT; 135mg/kg). Increases were observed in ACTH (LOEL, 12.5mg/kg), CORT (LOEL, 5mg/kg) and progesterone (LOEL, 5mg/kg) 15min following a single dose of ATR. DACT (135mg/kg) increased ACTH (1.3-fold), CORT (2.9-fold) and progesterone (1.9-fold) above vehicle control concentrations, but the magnitude of the responses was much lower than that observed for an equal molar dose of ATR (200mg/kg; 7.0, 9.0 and 11.0-fold above ACTH, CORT, progesterone controls, respectively). CTA results demonstrated conditioned taste avoidance to ATR, with a NOEL of 5mg/kg. Animals dosed with DACT developed avoidance responses comparable to the highest dose of ATR. In the pica experiment, lower doses (5–50mg/kg) of ATR had no effect on pica behavior, as measured 6 and 24h post-dosing, nor did DACT. However, the highest dose of ATR (200mg/kg) did induce pica behavior at both time points. No differences in body temperature were observed. Overall, results indicate that increases in ACTH and CORT secretion following administration of ATR occur at doses that are without effect on the display of pica behavior, indicating that the HPA-axis activation caused by ATR is not likely the result of gastrointestinal distress.