A patient with combined factor V and factor VII deficiency is described together with a family study. The propositus appeared to be double heterozygous for factor V and factor VII deficiency. Since the patient showed a parallel decrease of activity and antigen, he appeared to be double heterozygous for a true deficiency. The patient had inherited the factor V defect from the mother and the factor VII defect from the father. The parents of the propositus were not consanguineous. Other family members were found to have isolated factor V or factor VII deficiency. This is the third family so far described with this peculiar combined defect but the first to be investigated by clotting and immunologic assays.