During the last few decades there has been a steady rise of the incidence of upper urinary tract stones in the industrialized countries. Dietary factors, mainly an increased consumption of animal protein, probably explain part of this dramatic change. Little is, however, known how other components of the altered life styles might affect the propensity for stone formation. The prevalence of renal stones, as obtained in postmortem or radiographic studies, is 1-3% without apparent sex differences. In several unselected population surveys the life time risk for males approaches 20% while for females it is 5-10%. The recurrence rate is high and around 50% will experience another stone within 5 years from the onset. The annual incidence is around 1% in males with a peak in the fifth decade. Thus upper urinary tract stones are much more common than is generally appreciated, but most studies of their pathophysiology are only concerned with the small fraction of patients that is investigated in specialized research clinics.