The rate of spontaneous and mitomycin C induced chromosome breakage and sister chromatid exchange (SCE) was studied in three related cases diagnosed with VACTERL-H syndrome. There have been recent reports of sporadic patients with VACTERL-H in whom high rates of chromosome breakage were observed. This has led to the suggestion that some of these patients may represent the severe expression of Fanconi anemia. The pattern of inheritance in our family is highly suggestive of X-linked recessive inheritance supporting the hypothesis that VACTERL-H is, at least in some cases, a syndrome and not an association.