The clinical and histopathological findings are reported in 3 primary malignant lymphomas of the lower urinary tract. Two arose in the bladders of a 70-year-old man and a 67-year-old woman. The first was histologically low grade and the patient remains free of disease after more than 7 years. The second was an intermediate grade neoplasm and the patient died after 39 months. The third tumour was found in the urethra of a 76-year-old woman and it appears to represent only the third primary malignant lymphoma described at this site. The bladder is an uncommon primary site of extranodal lymphoma. Most patients present with haematuria and cystoscopy shows 1 or more solid, round, tumour-like masses. Histological grade, particularly follicle formation, appears to have predictive value.