Sexually mature Charles River Sprague Dawley CD outbred male rats received topical applications of hair dyes twice weekly for 10 weeks. They were then mated to one sexually mature female of the same strain each week for three weeks. One hundred F1 males from these matings, maintained under standard conditions for 12 weeks, were paired with one mature female per week for three weeks. The pregnancies were interrupted after approximately 16 days and the numbers of live and dead fetuses and implantations and resorptions were recorded. Fertility rates were high for both generations. Average litter sizes for the two hair dye groups and the control in the F1 generation were nearly identical and were in excess of 11 live pups per litter. There is no evidence from these results that frequent topical applications of hair dyes cause stable chromosomal rearrangements, such as translocations, which may result in reduced fertility of the offspring of the treated subject.