Adult patients with chronic iron overload were given oral ascorbic acid and continuous intravenous infusions of deferoxamine mesylate. The dosage of deferoxamine mesylate was altered every 48 hours from 1 g/sq m/24 hr to 2 or 4 g/sq m/24 hr. The average iron mobilization was 55.6 mg per day at the 1 g/sq m/24 hr dosage level, 78.6 mg every 24 hours at the 2 g/sq m/24 hr dosage level, and 90.1 mg every 24 hours at the 4 g/sq m/24 hr dosage level. Iron mobilization was undiminished when successive 14-day courses of deferoxamine separated by six-week intervals were administered.