We report on two sisters with mandibulofacial dysostosis (MFD). Both parents were examined carefully by clinical, radiographic, audiologic, and cephalometric methods. Neither showed evidence of the MFD gene. Photographs of three grandparents and examination of one disclosed no evidence of MFD. The parents are from the Hutterite Brethren and are consanguineous. Examination of the literature on MFD disclosed a number of other families with affected sibs and apparently normal parents. These families raise the possibility of an autosomal recessive form of MFD or some other explanation such as germinal mosaicism, chromosome rearrangement, or delayed mutation. For our family, the recurrence risk is probably 25%, but since germinal mosaicism cannot be excluded, it could be as high as 50%.