Cytogenetic studies were performed on 57 families with pregnancy wastage (eg, two or more spontaneous abortions or stillbirths). Chromosomal abnormalities were ascertained in 17 couples, through offspring with congenital malformations. Seven families had children with neural tube defects, and five families also had a previous child with Down syndrome. One mother had mosaic Turner syndrome; two additional mothers and one father had balanced chromosome translocations. These findings indicate that chromosome analyses should be performed on every couple with repeated miscarriages or malformed children, and subsequent pregnancies at risk should be monitored by amniocentesis.