A total of 43 cases of postirradiation prostate cores were assessed in an attempt to determine if routine use of alpha-methylacyl-CoA racemase (AMACR) in conjunction with high-molecular weight cytokeratin (HMWCK) would increase the recognition of carcinoma in postirradiation prostate biopsies. We concluded that in most cases the addition of AMACR in conjunction with HMWCK does not increase the recognition of prostatic adenocarcinoma, however it is supportive in nature. In one case the use of AMACR highlighted the extent of the adenocarcinoma which otherwise would have been designated as atypical small acinar proliferation (ASAP). Further evaluation is required to assess the significance of a diagnosis of atypical small acinar proliferation in postirradiation prostate biopsies.