Congenital horizontal gaze paralysis is a rare disorder which may be associated with severe scoliosis of early onset. We present the clinical findings of two sisters with this syndrome. The additional finding of a unique pericentric inversion of chromosome 12 is considered to be incidental. Every child with congenital horizontal gaze paralysis should be evaluated for a possibly associated scoliosis. If present, a diagnosis of this presumably autosomal recessive syndrome can be made with appropriate treatment and genetic counseling.