Expressions of telomerase genes (hTR, hTRT) and apoptosis related genes (p53, bcl-2) were detected by in situ hybridization and expression of the mutant p53 protein was detected by immunohistochemistry were detected in 44 patients with mammary atypical ductal hyperplasia, those expression were compared with those of the 6 benign hyperplasia and 26 breast carcinoma.