The records of 180 patients definitively irradiated for newly diagnosed adenocarcinoma of the prostate between 1970 and 1988 at Duke University Medical Center (107 patients from 1970-1983) and Moore Regional Hospital (73 patients from 1981-1988) were reviewed to determine the impact of overall treatment time on survival, local control, disease-free survival, and time to distant metastases. Using multivariate analysis we controlled for the influence of the following prognostic variables in addition to overall treatment time: age, clinical stage, histologic grade, acid phosphatase, type of biopsy, radiation dose, and use of hormonal therapy. Median follow-up was 46 months. Eighty-three percent of patients had clinical Stage B or C tumors. This is the first study to consider how treatment time might interact with recognized prognostic variables to influence treatment outcomes in prostate cancer and we found that overall treatment time did not significantly influence any of the outcome endpoints. Future research designed to improve local control after radiotherapy for prostate cancer should not focus on altering treatment time, but should explore other avenues such as hyperthermia, chemical modifiers or conformal therapy.