Klippel-Feil syndrome (KFS) displays congenital fusion of the cervical vertebrae; it is a relatively common condition and has many associated malformations such as Sprengel's deformity, scoliosis, rib anomalies, congenital defects of the brain or spinal cord, renal anomalies, congenital heart disease, deafness, cleft palate, cranial and facial asymmetry, and enteric cysts. There are various types of cervical fusion observed in KFS. However, fusion of the odontoid process with the atlas is a very rare finding. We report here on a 4-year-old boy with unilateral fusion of a separated odontoid process with the lateral mass of the atlas, and this was associated with a spontaneously closed ventricular septal defect, a small patent ductus arteriosus and a horseshoe kidney.