Epidemiological study of urinary stone colics was done for 5 years in a defined basin located in the center of Japan. It was 2.5 times more frequent in males than in females. The difference was observed only in the age over 30 years. Recurrence occurred in 24.5% of the cases. Climatic factors were also analysed. The incidence was significantly high in summer and low in autumn. Days of decreasing air pressure and high temperature were frequently associated with stone colic.