Using multiple chromosomal banding techniques, we studied a child with typical cat-eye syndrome and ocular retraction syndrome. Although the mother was was chromosomally normal, other maternal relatives showed features of the cat-eye syndrome, suggesting the basic abnormality is heritable. The abnormal chromosome in our case was most likely the product of reciprocal translocation where short arm plus centromeric chromatin from two separate acrocentric chromosomes fused together. The chromosomes involved were probably No. 22 and either Nos. 13 or 14. The basic underlying defect in cat-eye syndrome may be a heritable fragile site or some other predisposition leading to complex chromosomal interchange.