The purposes of this study were to characterize measures of fluid intake and perception of thirst in women over a 6-week period of exercise-heat acclimation and outdoor training and examine if this lengthy acclimation period would result in changes in fluid intake that differ from those previously reported in men utilizing a shorter acclimation protocol of 8-10 days. Voluntary water intake (11-17 degrees C) and perception of thirst were measured in a group of 5 women (21-26 yr) undergoing exercise-heat acclimation for 90 min/day, 3 days/wk (36 degrees C, rh 50-70%) and outdoor training 3 days/wk for 6 weeks. Decreased drinking during acclimation was characterized by a decrease in the number of drinks (35 +/- 10 to 17 +/- 5; p <.05), greater time to first drink (9.9 +/- 2.0 to 23.1 +/- 4.7 min; p <.05), and a decrease in total volume ingested per week (3310 +/- 810 to 1849 +/- 446 ml; p <.05) through the 6-week study. Mean perceived thirst measurements remained low and showed only slight variance (3 +/- 0.4 to 5 +/- 0.4). These observations support a psycho-physiological response pattern different than that previously observed during 8-10 day acclimation protocols in men.