Male and female Fischer rat pups received sc injections of 1.5 or 3 mg/kg of triethyl tin bromide (TET), ethanol vehicle or distilled water on day 5 postpartum. At 21, 28, 60, and 90 days of age, the rats were weighed and assessed in a battery of tests which included fore- and hindlimb grip strength, negative geotaxis, startle responsiveness and spontaneous motor activity. Animals at 60 days of age were also tested in a two-way shuttle box avoidance procedure. Exposure to TET did not affect body weight at any time during testing, nor did it affect negative geotaxis of grip strength, Startle response to an air puff stimulus was decreased in males and females at 21 and 60 days of age, while no effects were observed at 28 or 90 days of age. Responsiveness to an acoustic stimulus was decreased at 60 days of age only. Spontaneous motor activity of males was increased at 21, and 28 and 60 days of age, while females had elevated activity at 28 and 60 days of age. Relative to ethanol controls, rats of both sexes were significantly hypoactive at 90 days of age. In a two-way shuttle box procedure, latencies to emerge prior to the first trial were elevated in TET exposed male and female rats. The number of discriminated avoidance responses made during a 60 trial session was decreased in females receiving the 3 mg/kg dose. Activity during the intertrial interval was not affected. A single postnatal exposure to TET can produce long-term alterations in the sensorimotor capabilities of rats; the effect appears to occur equally in both sexes and is independent of toxicant-induced body weight changes.