The aim of the study was to evaluate factors of progression after radical prostatectomy in patients with bladder neck invasion (BNI). From 1988 to 2006, 1395 patients underwent radical prostatectomy, 120 (8.6%) had microscopic BNI (pT4 N0, TNM 2002). Group 1 was defined as BNI alone, group 2 as BNI plus extracapsular extension and group 3 as BNI plus seminal vesicle invasion (SVI). Postoperative follow-up data were obtained through routine serum prostate-specific antigen (PSA) and digital rectal examination. Biochemical progression was defined as a single detectable PSA level postoperatively (>0.2 ng ml(-1)). Groups 1, 2 and 3 included 38 (31%), 35 (30%) and 47 (39%) patients, respectively. Preoperative PSA (11.1 vs 24.7 and 23.3 ng ml(-1), P=0.01), biopsy Gleason score (5 vs 6 and 6, P=0.003) and specimen Gleason score (6 vs 7 and 7, P=0.02) were statistically different between three groups. None of the patients had a specimen Gleason score >or=8 in group 1. After a mean follow-up of 27 months, 51 (42.5%) patients had biochemical progression. The 5-year progression-free survival was 87, 53 and 17% for groups 1, 2 and 3, respectively (P<0.001). Within pT4 prostate cancer, those tumors with isolated microscopic BNI appear to have better prognosis than those with associated extracapsular extension and/or seminal vesicle invasion, and should be distinguished in TNM classification.