Fifty-eight children who underwent diagnostic femoral artery catheterization before 5 years of age, from 5 to 14 years before the study, were randomly selected from approximately 300 surviving patients undergoing diagnostic femoral artery catheterization at our institution during the interval. Each patient underwent vascular laboratory segmental pressure and waveform examination and arterial duplex scanning, as well as lower extremity bone length radiographs, which were considered positive if the catheterized leg was greater than or equal to 1.5 cm shorter than the opposite leg. Thirteen children who had only venous catheterization served as controls. No arterial abnormalities were present in the control patients (mean ankle/brachial index, 1.01). Arterial occlusion was present in both limbs of five patients who had bilateral diagnostic femoral artery catheterization and in 14 limbs of 51 patients who had unilateral diagnostic femoral artery catheterization. Thus arterial occlusion was present in 33% of patients (19 of 58) and in 37% of limbs (24 of 65). The mean ankle/brachial index in the catheterized limbs was 0.79. Leg growth retardation was present in four limbs (8%) of 51 children undergoing unilateral diagnostic femoral artery catheterization and in one (8%) control patient. The inverse relationship between ankle/brachial index and leg growth retardation was significant (R = 0.47, p less than 0.0005). Only one patient had symptoms of arterial occlusion (claudication), and one patient had symptoms of leg growth retardation (gait disturbance). We conclude that arterial occlusion is common after diagnostic femoral artery catheterization in children less than 5 years of age, but that excellent collateral supply prevents leg growth retardation and/or symptomatic arterial insufficiency in most children.(ABSTRACT TRUNCATED AT 250 WORDS)