Transformation of chick embryonic fibroblasts with Rous sarcoma virus strongly suppresses N‐cadherin‐mediated cell‐cell adhesion, without inhibiting its expression. This suppression is correlated with tyrosine phosphorylation of N‐cadherin and catenins, the cadherin‐associated proteins, which are known to regulate cadherin function. Experiments with non‐myristylation and temperature‐sensitive mutants of RSV and with herbimycin A, a potent inhibitor of tyrosine kinases, suggest that both the suppression of cell adhesion and tyrosine phosphorylation of catenins are highly transformation‐specific.