Eleven pure apocrine carcinomas (8 breast, 2 vulvar, 1 axillary) were evaluated for the presence of androgen and estrogen receptor mRNA. These immunohistochemically androgen receptor positive and estrogen receptor negative cases were microdissected and analyzed by the reverse transcription polymerase chain reaction for the presence of receptor message. Nine of these 11 estrogen receptor (ER) negative lesions were found to contain the ER mRNA through the first intron splice region. In 4 of the 11 cases, the androgen receptor (AR) mRNA could not be shown even though the protein was detected immunohistochemically. In the other seven, AR mRNA was identified. This indicates that the mechanism for production of the estrogen receptor is intact and functional in most cases through the first transcriptional splice region. Therefore, the immunohistochemical absence of the estrogen receptor in apocrine cells cannot be explained by an abnormal message at these common sites and should be sought beyond these points.