Coagulation studies were performed in 16 children with steroid responsive minimal change nephrotic syndrome in order to elucidate the incidence of thromboembolic complications. Fibrinogen and alpha 2-macroglobulin concentrations were inversely correlated with serum albumin concentrations, antithrombin III correlated positively (p less than 0.001). Factor VIII:R:AG concentration was elevated. Coagulation disturbances in children are not less severe than in adults with nephrotic syndrome. Combined scintigraphic pulmonary ventilation and perfusion studies were employed in 26 children to detect noninvasively events of pulmonary embolism, respectively their residual changes. The lung scintigraphic investigation demonstrated a pattern consistent with pulmonary embolism in 7 patients (27.9%), residual changes in 10 (38.5%) and normal findings in 9 (34.9%). The incidence of thromboembolic complications in children with severe nephrotic syndrome is as high as reported for adults. Pulmonary symptoms may well be due to pulmonary embolism.