A new syndrome: multiple congenital abnormalities and mental retardation in two brothers: In this report we present two brothers with abnormal neurological development, hypotonia, short stature, pylorus stenosis, pectus excavatum, brachycephaly due to craniosynostosis, frontal bossing, depressed nasal bridge, high arched-wide palate, downslant palpebral fissures, low-set, large ears, thin upper lip and bilateral cryptorchidism. The brothers were born to a couple of second cousins and were the third and fourth pregnancies of the mother. The father, the mother and the eldest sibling were phenotypically and chromosomally normal. The clinical findings of the brothers were found to be similar. These clinical findings were compared with syndromes showing some of the symptoms, namely Apert, FG, Floating-Harbor, Shprintzen-Goldberg and Rett Syndromes. However, when the findings were detailed, we observed that they did not match completely any of the syndromes in a discernable way. The MECP2 gene mutation was analysed because of mental retardation, poor neurological evolution and large ears, but no mutation was found. So these cases are presented as a new syndrome with apparent autosomal recessive inheritance.