Thirteen men and one woman (mean age 48.8 yr +/- 6.9, range 36-63) with idiopathic hemochromatosis were treated by erythrocytapheresis. Iron depletion followed 9.60 months treatment (median 24), with 21-203 erythrocytaphereses (mean 93 +/- 61) and total iron removal of 4.2-40.6 g (mean 19 +/- 11.9). Trasferrin saturation decreased from 90 +/- 8.7% to 17 +/- 10.6% and serum ferritin from 3164 micrograms/L +/- 1488 to 60.5 micrograms/L +/- 77.5, and liver iron content normalized in all cases. Initial serum ferritin in the patients who were iron-depleted at 18 months (50%, cumulative percentage) was significantly lower than in those still iron loaded at that time (2280 micrograms/L +/- 940 vs 4049 micrograms/L +/- 1444, p less than 0.02). Clinical improvement was noted in all cases with about a 30% decrease in insulin requirement in most diabetics. Thus erythrocytapheresis appears to be effective and safe in obtaining iron depletion in idiopathic hemochromatosis.