Objective To establish the relationship between tumour volume (TV), pathological stage and outcome after radical prostatectomy (RP), as TV is theoretically an important variable in prostate cancer pathology, but to date it has not been routinely reported and its independent prognostic significance is not well defined. Patients and Methods The study included 431 consecutive patients undergoing RP for clinically localized cancer, from January 2000 to January 2002, who had a pathological examination of totally submitted whole-mount processed RP specimens. In addition to Gleason grade, tumour stage and margin assessment by standard techniques, TV was determined by digital planimetry. The total TV or index TV, for cases with obvious discrete separate tumours, were correlated with pathological stage and prostate-specific antigen (PSA) recurrence. Results The mean (range) follow-up was 25.4 (6-51) months, and the mean TV for all patients was 3.28 (0.4-38.8) mL. There was a direct correlation between TV and pathological stage (P < 0.001). The TV for organ-confined and extraprostatic disease was 2.09 and 6.02 mL, respectively (P < 0.001). In a multivariate analysis, TV was an independent predictor of PSA recurrence (P = 0.04). The mean TV for patients with PSA recurrence vs no recurrence was 6.8 and 2.6 mL, respectively (P < 0.001). Conclusion TV correlates directly with pathological stage in RP specimens; furthermore, it is independently correlated with PSA recurrence. TV has potential use for prognostication in patients undergoing RP, and may be combined with other well established clinical variables to aid in predicting outcomes.