Objective: We present 267 patients undergoing surgery for renal carcinoma, comparing the incidental tumour and symptomatic tumour with different parameters and evaluating the prognostic significance of the incidental diagnosis., Material and Methods: Of the 267 patients, 110 (41.2%) were diagnosed incidentally. The different variables analysed were: age, sex, tumour size, if unilateral or bilateral, histological type, stage, degree of cellular differentiation and survival. The mean follow-up period was of 43.32 mos in the symptomatic patients and 41.85 mos in the patients diagnosed incidentally. The data obtained was analysed with the SPSS statistic pack., Results: No significant difference was detected between both groups in regards to age, sex, if unilateral or bilateral and histological type. Comparing tumour size, a statistic difference was observed with slices at 6 cm. When analysing the stage and degree of cellular differentiation, a significant difference is found with tumours diagnosed incidentally presenting better differentiation and a lower stage at the moment of diagnosis. Survival after 5 yrs was of 65.7% for symptomatic patients in comparison to 81.7% for the incidental group, which implies high statistical signification (log rank = 0.0018)., Conclusions: In our series no significant differences were detected between incidental and symptomatic tumours when comparing age, sex, anatomic side and histological type. Significant differences were indeed detected in relation to size, degree of cellular differentiation, tumour stage and survival.