An overdose of digoxin was documented in two suicidal patients by a radioimmunoassay method. One patient survived despite a serum digoxin level of 20 ng/ml. In the other patient, who died shortly after admission, the serum digoxin level was 25 ng/ml. Sequential serum digoxin levels in the surviving patient indicated a serum digoxin half-life of 15 hours. This short half-life may be due to the large amount of unbound digoxin in the serum and tissues. The usual means of removing ingested toxins from the stomach should be applied with caution in a digoxin-toxic patient because of the hazards of increased vagal activity and high degrees of heart block.