The accuracy of preoperative and histopathological diagnosis of vascular tumours and tumour-like lesions was studied in 130 patients and 185 specimens. A correct clinical diagnosis was made before operation in 66% of the patients, whereas in the others a microscopic examination was necessary to determine the exact nature of the lesion. The histological picture was retrospectively correlated with all available clinical information and the original histopathological diagnosis, and re-evaluated: it was correct in 53%, imprecise in 32% and false in 15% of the cases. The microscopic diagnostic criteria for the different types of vascular lesions are discussed and a revised classification is presented. The study shows that close cooperation between the pathologist and the clinician is necessary for obtaining an accurate diagnosis of vascular tumours and tumour-like lesions.