Nine painted turtles having body sizes ranging from 69 to 408 g were exposed to 17β-estradiol equivalent doses of nominal concentrations of 0.15 ng/l ‘Low’ dose; 1.5 ng/l ‘Medium’ dose; and 15 ng/l as ‘High’ dose (n=3 per dose group). Turtles were randomly assigned into each exposure group, but ensuring equal size distribution between the three groups. The low and medium doses fall within the range of E2 determined at our study sites via RIA, and the high dose represents expected levels in the fall and levels determined by RBA. Turtles were housed individually in 10 gallon glass aquaria containing 6 l well water, with a glass dish provided as a basking platform. Room temperature was maintained at 25°C with a 14 l:10 D photoperiod throughout the experiment. Turtles were fed every 2–3 days and exposure medium changed and re-dosed daily for 28 days.