Over a period of 7 years a typical hemolytic uremic syndrome (HUS) developed in 3 brothers, at the age of 27, 31 and 35 years respectively. The patients did not share a common HLA haplotype. Two sisters, now 36 and 39 years old, did not develop HUS despite pregnancy and prolonged oral contraception. We investigated in the 3 patients (outside of the acute phase of the HUS) and in 12 other first degree relatives complement components (C3, C4, C1q, factor B), coagulation factors (i.e., antithrombin III, F VIII, protein C) prostacyclin regulating plasma factor and vitamin E levels: all results were normal. Renal failure was irreversible in the 3 patients, despite fresh plasma infusions in 2 of them. After a 7 to 32-month period on hemodialysis, the 3 patients were transplanted with a cadaver kidney. Twenty-one to 94 months later, they have a functioning graft and no recurrence of the HUS. We conclude that, in this family, HUS is not linked to HLA or female gender. No phenotypic marker of the disease was found. Evolution after dialysis and transplantation is excellent, with no short term recurrence of the HUS.