BACKGROUND: In a recent study of three families we have found that inherited haemolytic uraemic syndrome (HUS) maps to a region of chromosome 1q containing the gene for complement factor H. In one of these families and also in a case of sporadic D-HUS, we have identified mutations in the factor H gene. A further family with inherited HUS has therefore been investigated. METHODS: DNA extracted from the family members and DNA extracted from archival post-mortem material from a deceased family member, was studied. Review of renal biopsies and study of complement components was also undertaken. RESULTS: This family demonstrates an inherited deficiency of complement factor H. Non-diarrhoeal HUS has affected at least two family members with half normal levels of factor H. CONCLUSION: These findings represent further evidence of the association between factor H dysfunction and HUS.