In adult patients with ESRD, calcific uremic arteriolopathy (CUA) is an uncommon but life-threatening complication. No effective therapy exists, although anecdotal case reports highlight the use of sodium thiosulfate (STS), a calcium-chelating agent with antioxidant properties. CUA is rare in children, and STS use has not been reported. The objective of this study was to determine the influence of STS treatment on three patients with CUA in a pediatric chronic dialysis unit. The patients were between 12 and 21 yr of age; two were male; and primary diagnoses were obstructive uropathy, renal dysplasia, and calcineurin nephrotoxicity. Time from ESRD to CUA diagnosis was 1, 9, and 20 yr. Diagnosis was made by tissue biopsy and three-phase bone scan. Pain was the presenting symptom. Initial treatment included discontinuation of calcitriol and use of non-calcium-based phosphate binders and low-calcium dialysate concentration. STS dosage was 25 g/1.73 m(2) per dose intravenously after each hemodialysis session. For optimization of removal of calcium deposits, patient three received a combination of STS and continuous venovenous hemofiltration for the first 10 d. All patients demonstrated rapid pain relief. Within weeks, skin induration and joint mobility of the extremities improved. Radiographic evidence of reduction in the calcium deposits occurred within 3 mo of initiation of STS. The only complication was prolonged QT interval in one patient as a result of hypocalcemia, who was resolved by use of a higher dialysate calcium concentration. STS seems well tolerated in children and young adults with CUA and has mild adverse effects. For determination of its efficacy, optimum dosage, duration of therapy, and dialysis modality, controlled trials are needed.