This study, conducted for Schering AG and M & T Chemicals, was designed to evaluate the effects of Bis (tri-n-buty1tin) Oxide (T8TO) on the growth, reproductive performance and fertility of rats through two consecutive generations (FO,F1). Test article was mixed with the granulated diet and administered to male and female CD* rats (30/sex/group) at fixed concentrations of 0.5, 5.0 and 50.0 ppm. Included in this study was an untreated diet control group (30/sex). FO adult generation animals were treated over a 10-week premating treatment period and continued to be exposed to treated diets during the ensuing mating, post-mating (males and unmated females), and gestation/lactation intervals of the Fi litters until sacrificed. Fl pups (two/sex/litter) selected at Day 21 (weaning) became a pool of animals from which the Fl adult generation was selected. These pups which had initiated consumption of the dam's diet during lactation continued to consume diets of these same treatment levels during a post-weaning interval and through a 15-week pre-mating treatment period. F1 animals continued on treatment during the ensuing mating period, post-mating period (males and unmated females) and gestation and lactation intervals of the F2 litters until sacrificed. Litter size, pup weight data and pup sex distribution data were recorded at regular intervals during the 21-day lactation period. Litters were culled to four pups/sex when possible, on Day 4 of lactation. Pups were weaned on Day 21 of lactation.