Urolithiasis is a lifestyle disease. Sex, age, race, place of residence (geographical region), chronic diseases, lifestyle (including diet) and various genetic factors contribute to the risk of calculus formation within the urinary tract. The prevalence of urolithiasis in adults ranges from 1 to 20%, and children account for 2–10% of patients. The annual incidence of paediatric urolithiasis is estimated at several cases per 100,000 children worldwide; it is the reason for approximately 1 per 1,000 hospitalisations among paediatric patients. The prevalence of urolithiasis has been increasing in both adults and children. In young children, the disease is usually a result of a genetically determined metabolic defect (such as hypercalciuria, distal tubular acidosis, familial hypomagnesaemia with hypercalciuria and nephrocalcinosis, or Lesch–Nyhan syndrome). Another significant risk factor in children is a urinary tract defect with urinary retention. Urinary tract infections, in turn, may be either a cause or a complication of urolithiasis. In older children and adults, malnutrition, obesity and metabolic syndrome play a significant role. Other factors conductive to urolithiasis are: certain drugs, low level of physical activity, long immobilisation, low fluid intake, warm climate, inadequate diet and improper vitamin D₃ supplementation. The disease recurs within 5 years in 50% of patients. Urolithiasis and its complications may lead to end-stage renal failure. The disease can be divided into different types based on the chemical composition of a calculus, aetiology of the disease and site of calculus formation (upper or lower urinary tract). The composition of calculi is quite often mixed, and they form due to various causes.