Sixty-one surgical departments in Denmark were asked how they used the three possible diagnoses: carcinoma in situ vesicae urinariae (D09.0), neoplasma benignum vesicae urinariae (D30.3) and neoplasma malignum vesicae urinariae (C67.9) for bladder tumours with specific reference to different stages and grades of the tumour. The answers from 59 departments demonstrated great variation in the classification of the same bladder tumour. This variation results in a registration of data which is not valid for a statistical outcome of the real incidence of benign and malignant bladder tumours in Denmark. A consensus from the Danish Bladder Cancer Committee, which will be published in 1996, concerning the criteria for the use of the different diagnoses for bladder tumours, should however in the future make it possible for all departments to make a uniform classification.