PURPOSE: We evaluated urinary collecting system invasion as a prognostic parameter of renal cell carcinoma. MATERIALS AND METHODS: A total of 1,124 patients who underwent nephrectomy for a renal tumor at 5 European centers were included in this retrospective study. Several variables were analyzed including urinary collecting system invasion, age, sex, TNM stage, Fuhrman grade, histological subtype, Eastern Cooperative Oncology Group performance status and cancer specific survival. RESULTS: There were 771 males (68.6%) and 353 females (31.4%) in this study, and median age was 61 years (range 14 to 88). Median tumor size was 6 cm (range 1 to 24). Tumors were organ confined and Fuhrman grade was recorded as 1 or 2 in 67.1% and 62.3% of cases, respectively. Symptoms were present at diagnosis, and Eastern Cooperative Oncology Group performance status was 1 or more in 50.3% and 16.1% of the cases, respectively. Median followup was 43 months (range 1 to 299). At the end of followup 246 patients (21.9%) died of cancer. In 132 cases (11.7%) urinary collecting system invasion was noted. Urinary collecting system invasion was associated with symptoms, TNM stage, Fuhrman grade, tumor size (p <0.001) and Eastern Cooperative Oncology Group performance status (p = 0.003), but not with histological subtype (p = 0.7). On univariate analysis TNM stage, Fuhrman grade, symptoms, Eastern Cooperative Oncology Group performance status, tumor size and urinary collecting system invasion (p = 0.0001) were significant predictors of cancer specific survival. Urinary collecting system invasion was an independent prognostic parameter only in the setting of pT1-T2 tumors. When the urinary collecting system was invaded the 5 and 10-year probabilities of survival were 43% and 41%, respectively. CONCLUSIONS: Urinary collecting system invasion appears to be an independent prognostic parameter of organ confined renal cell carcinoma. Our data support the need to integrate this parameter in further TNM revisions.