Congenital factor VII (FVII) deficiency is an autosomal recessive bleeding disorder with variable phenotypic correlation between FVII activity and bleeding risk. We report a novel mutation of the FVII gene that creates the amino acid change Ser 103 to Gly, which resulted in severe FVII deficiency with reduced FVII antigen. This mutation in the heterozygous form was also present in a mildly affected, unrelated patient. We also report on the natural history of an FVII inhibitor in the patient with severe FVII deficiency.