Cadherins are Ca(2+)-dependent cell adhesion molecules that play essential roles in organogenesis. Northern blot analysis was used to determine the levels of epithelial (E)-, neural (N)-, and placental (P)-cadherin expression in developing rat testes from 1-, 2-, 3-, and 4-wk-old rats. Highest expression of all three cadherins occurred during the first two postnatal weeks, prior to the establishment of the blood-testis barrier. Transcripts of all three cadherins were also detected in RNA isolated from Sertoli cells cultured from 3-wk-old rat testes. Immunoblot analysis demonstrated levels of E- and P-cadherin protein in the testis and Sertoli cells that corresponded to the levels of their respective RNA transcripts. Immunohistochemical reactivity of E-cadherin in 8-day-old mouse testis was associated with germ cells situated basally in the seminiferous tubules. This report establishes the expression of E-cadherin in the testis and the simultaneous expression of E-, N-, and P-cadherin in both testis and Sertoli cell cultures.