OBJECTIVE To evaluate a contemporary series of patients with incidental prostate cancer detected by transurethral resection of the prostate (TURP) and undergoing radical prostatectomy (RP). PATIENTS AND METHODS Between 1998 and 2004, 1931 patients had TURP for obstructive voiding symptoms and suspected BPH. Incidental prostate cancer was found in 104 (5.4%); 26 of these patients had a RP. The pathological staging and treatment of these patients were reviewed retrospectively and the follow-up results obtained. RESULTS Of the 26 patients who had RP, 17 had T1a and nine had T1b carcinoma of the prostate. After RP, six (35%) in the T1a group had no residual tumour (pT0) and 11 (65%) had pT2 cancer; the respective incidence in those with T1b was two and seven, with no pT3 disease in either group. The preoperative Gleason grading did not correspond well with that after RP; 30% of the patients had upgraded Gleason scores and 42% showed either downgrading or no residual tumour, with 81% having Gleason scores of <7. After a median follow-up of 47 months, one patient is receiving hormonal therapy because of biochemical relapse. Conclusion Subsequent to stringent PSA testing and prostate biopsy when indicated, the rate of incidental prostate cancer is low. Furthermore, substantially many patients will harbour either no residual cancer or tumours with favourable characteristics in their RP specimens. However, there is currently no possibility to reliably predict the absence of aggressive prostate cancer after TURP, and thus safely recommend observation instead of further therapy. Therefore, patients with incidental prostate cancer need to be counselled individually. The decision 'treatment or no treatment' should be determined by the patients' age and life-expectancy, tumour aggressiveness in the TURP specimen and the prostate-specific antigen level after TURP.