Female rats were given by gavage every other day from days 2 to 20 of gestation an aqueous solution of trioxane at daily doses equal to 0.025; 0.075 and 0.15 LD50 (0.19: 0.58 and 1.16 g/kg). Maternal exposure to trioxane at the highest dose resulted in death of most neonates a few days after birth. Viability and postnatal growth of the offspring of dams that were given 0.19 and 0.58 g/kg were not affected. Transitional depression of exploratory locomotor activity in female offspring and a decrease of active avoidance acquisition were observed in adult male and female offspring from the 0.58 g/kg group, whereas a dose of 0.19 g trioxane /kg did not affect the behavioral performance of progeny.