These studies were performed to evaluate the reproductive and developmental toxicity of pyridostigmine bromide (PB) in rats. Separate male and female fertility/reproductive performance studies, a perinatal/postnatal study and a teratology study were conducted. Dose levels were sufficient to result in overt cholinergic tremors at the high dose in each study. PB did not affect male or female fertility/reproductive performance. Pups born to treated dams did show slight, transient decreases in body weight gain, apparently secondary to the nursing behavior of dams demonstrating overt tremors. PB did not result in an increase in visceral or skeletal malformations. A slight increase in delayed ossification and early resorption were seen at the highest dose tested and were considered secondary to maternal stress/toxicity.