Certain germline mutations (607Arg-Gln, 608Arg-Lys) in the androgen receptor gene have been associated with the occurrence of breast cancer in males suffering from partial androgen insensitivity. To assess whether somatic mutations in this gene could be detected in breast carcinoma, archival tumor tissue of males without clinical evidence of androgen insensitivity was screened for point mutations in the androgen receptor gene. DNA was retrieved by chloroform-phenol extraction from formalin-fixed, paraffin-embedded tissues. Exons 2-8 of the androgen receptor gene, encoding the DNA- and hormone-binding regions of the receptor, were amplified by polymerase chain reaction and subjected to nonisotopic single strand conformation assay (SSCA) to screen for point mutations. In the tumor DNA, no variations suggestive of mutations were encountered on SSCA. However, in a control patient with partial androgen insensitivity and predominantly female phenotype, the germline mutation 607Arg-Gln was identified in blood leukocyte DNA. Our results indicate that somatic mutations of the androgen receptor are not required for the development of male breast cancer. This, however, does not exclude an increased risk of breast carcinoma in patients with androgen insensitivity.