Citrate is thought to be one of the most important inhibitor of calcium salts crystallization in the urine. Therefore, an assessment of urinary citrate excretion is an integral element of metabolic evaluation in urolithiasis. The reported incidence of urolithiasis associated with hypocitraturia varies from 10% to 63%. The purpose of the study was to assess urinary citrate excretion in children with calcium urolithiasis living in region of Lublin. The study comprised 60 children (34 boys and 26 girls) aged 4.3-18 years. In 36 of them, calcium oxalate urolithiasis was diagnosed by spectrophotometry. In the remaining children, an assessment of stone composition was impossible. However, in all children, stones were radiopaque. Hypercalciuria (HC) and mild hyperoxaluria (HOx) were diagnosed in 23 and 16 children, respectively. In the remaining 21 children urolihiasis was classified as idiopathic. The controls were 35 healthy age- and gender-matched children. Urinary citrate excretions were assessed by enzymatic method in 24-hour urine specimens and expressed as citrate/creatinine ratios (Cit/Cr). Decreased Cit/Cr were observed in 9 (15%) children with calcium urolithiasis. However, there was no significant difference between the mean Cit/ Cr in children with calcium urolithiasis and controls (410 +/- 207 mg/g vs 385 +/- 144 mg/g). There was also no significant difference between the mean Cit/ Cr in children with HC and controls. Similarly, the mean Cit/Cr did not differ significantly between children with HOx and controls. However, the lowest mean Cit/Cr was revealed in children with HOx (306 +/- 161 mg/g). CONCLUSIONS In most children with calcium urolithiasis urinary citrate excretion was normal. However, in some children with urolithiasis, detection of hypocitraturia allows to explain pathogenesis of stone formation and to carry on a causative prophylaxis.