We present 3 of 25 patients with massive, occult transition zone cancers 7 to 86 cc in volume. Despite serum prostate specific antigen (PSA) levels of 150 to 456 ng./ml. (Yang polyclonal assay), all 3 were organ confined at radical prostatectomy and have undetectable serum PSA levels by an ultrasensitive assay at 300 to 650 days postoperatively. This clinical syndrome includes a highly elevated PSA level, benign prostatic hyperplasia on digital rectal examination, a nondiagnostic transrectal ultrasound and frequently negative transrectal or perineal needle biopsies. Clinical recognition of this syndrome plus systematic biopsies of the transition zone are the keys to diagnosis and potential cure of these patients. These cases may explain the 10% rate of men who present with metastatic prostate cancer and a normal rectal examination, much of the discrepancy between focal cancer on biopsy and large cancers in radical prostatectomy specimens, and why some men have an extraordinarily high serum PSA level and organ-confined cancer at prostatectomy.