A 5-month-old female with the Coffin-Siris syndrome is described. Characteristic features included prenatal and postnatal growth retardation, slight mental retardation, feeding and respiratory problems, microcephaly, hypotonia, full lips, congenital heart disease, hypoplasia of the distal phalanges of the fifth fingers and toes. She underwent successful primary closure of a ventricular septal defect at 8.5 months of age, weighing 5.0 kg. After the operation, the feeding and respiratory problems disappeared, and growth and development were well maintained.