We describe a girl with motor and mental retardation, macrocephaly, a "coarse" face, choanal atresia, postnatal feeding difficulty, redundant skin with deep palmar and plantar creases, and histopathological evidence of altered elastic fibers, who died at the age of 11 months. We believe this represents another case of Costello syndrome. Lacking papillomata, she had choanal atresia and underwent a fatal outcome at an early age. The differential diagnosis of cutis laxa in association with postnatal growth retardation and developmental delay and with cardio-facio-cutaneous and Noonan syndromes is discussed.