Risk factors should be evaluated in all patients with urinary lithiasis. The kind of evaluation, simplified or extended, depends on stone composition and, in patients with calcium lithiasis, on the clinical presentation. These studies are done in an outpatient regimen, are easy to perform and accessible for most laboratories. Patients with uric acid, infectious and cystine stones only require a selective more abbreviated evaluation. In calcium lithiasis we perform an extended metabolic evaluation in recurrent patients and also in singleepisode patients when they have high recurrence risk. The extended evaluation has demonstrated to be costeffective in patients with highly recurrent lithiasis. There is not enough clinical evidence yet on what would be the most convenient study methodology for a proper metabolic evaluation, and proposed clinical guidelines are mainly based on expert committee opinions.With these studies, we can diagnose systemic and renal diseases of lithogenic nature, and they also enable the adoption of precise prophylactic measures that achieve recurrence control in a great number of patients.