alpha-Methylacyl-coenzyme A racemase (AMACR) has become a common tool in the diagnosis of morphologically difficult prostatic carcinoma and often is used in combination with the basal cell markers p63 and 34betaE12. Outside this context, applications have been limited. Although initially considered a specific marker of prostatic carcinoma, immunoreactivity for AMACR has been found in a variety of other neoplasms. We report findings in 21 cases of extramammary Paget disease (EMPD), a neoplasm not previously reported to show AMACR immunoreactivity. We found immunoreactivity for AMACR in 15 (71%) of 21 EMPD cases overall, in 5 (56%) of 9 cases in women, and in 10 (83%) of 12 cases in men. AMACR immunoreactivity is a common finding in EMPD in men and women.