Adhesion between germ and Sertoli cells is thought to be crucial for spermatogenesis. Cadherin superfamily proteins, including classic cadherins and protocadherins, are important mediators of cell-cell adhesion. Using a degenerate PCR cloning strategy, we surveyed the expression of cadherin superfamily members in rat testis. Similar to brain, testis expressed a large number of cadherin superfamily members: 7 classic cadherins of both types I and II, 14 protocadherins, 2 protocadherin-related cadherins, and 1 cadherin-related receptorlike protein. All three protocadherin families (alpha, beta, and gamma) were found in testis. Using a semiquantitative RT-PCR assay, messenger RNA expression was determined for each cadherin superfamily member during a postnatal developmental time-course and following ablation of specific testis cell types by ethanedimethanesulfonate, methoxyacetic acid, and 2,5-hexanedione. Diverse expression patterns were observed among the cadherins, suggesting that cadherin expression is cell type-specific in testis. The large number and variety of cadherin superfamily members found in testis supports a critical function for cadherin-mediated cell-cell adhesion in spermatogenesis.