The arterial resting flow, the arterial peak flow after 3 minutes of circulatory arrest to the leg, and the venous emptying rate were studied by strain gauge plethysmography in the calves of 85 children between 3 and 16 years of age. Most of the children had heart disease; therefore the values obtained can be regarded as reference values only for this type of patient.--The reproducibility of the results of the flow measurements was favourable and equal to that found in the examination of adults and of children using water-filled plethysmographs. --All of the flow functions investigated were significantly higher in the younger children and--but not always significantly--higher in boys than in girls. There was no difference between sides as regards arterial flow, whereas the venous emptying rate was significantly lower in the left calf. --Strain gauge plethysmography is recommended for assessment of circulatory complications after vascular catheterization in children aged 4 years or older.