Pulmonary calcifications are known to occur in patients with chronic renal failure. Recently, scintigrams with bone-seeking radionuclides have been used to detect subclinical pulmonary calcium deposits. We studied 18 children on maintenance dialysis without evidence of pulmonary calcification on chest X-ray. Four children (22.2%) had a positive technetium 99m hydroxymethylene diphosphate scan (group 1), and 14 children had a negative scan (group 2). Mean serum aluminum levels were 2.68 ± 0.30 μmol/l (mean ± SD) in group 1 as compared to 1.66 ± 0.72 in group 2 (p < 0.01). No significant difference was found between the groups with respect to serum levels of calcium, phosphorus, bicarbonate, magnesium and the calcium-phosphorus product as well as parathyroid hormone and vitamin D levels. The patients with pulmonary calcifications were on dialysis a significantly longer time than those of group 2 (62 ± 15 versus 35.7 ± 23 months; p < 0.01). These data show that pulmonary calcification occurs with high frequency in children undergoing long-term dialysis. They seem to be related to high serum aluminum levels. We propose that pulmonary scintigrams with bone-seeking radionuclides be used routinely for the diagnosis and follow-up of uremic pulmonary calcification.