Tritiated digoxin turnover studies were performed in nine children aged 4 days to 7 years. Mean serum turnover time was 32.5 (range 18-48) hours, and the 3-day urine and stool excretion was 55% of the total dose administered. These findings are quite similar to those observed in adults and indicate that the larger doses of digoxin required for digitalization in infants are not accompanied by increased metabolism or excretion but by increased blood levels and presumably increased tissue concentrations of the glycoside.