Several investigators have suggested that the Marshall syndrome and the Weaver syndrome are one entity because of some phenotypic overlap. This paper reviews the findings in nine additional patients with the Marshall syndrome and concludes that the syndromes are two distinct entities. In the Marshall syndrome there is a characteristic facies, failure to thrive in terms of height, weight, and psychomotor development, and early death. In the Weaver syndome the infants thrive too well: weight and heights are much above normal. They also have increased bifrontal diameters, hypertonia, prominent finger pads, and thin, deep-set nails, and the face is quite different from the Marshall facies.