Contemporary information on the trends and patterns of mortality associated with birth defects and genetic diseases is lacking in the United States. To study these trends and patterns, we used the Multiple-Cause Mortality Files of the National Center for Health Statistics. From 1979 through 1992, 320,208 deaths in the United States were associated with birth defects and genetic diseases. The age-adjusted mortality rates for people with birth defects declined from about 8.2/100,000 in 1979 to about 6.7/100,000 in 1992, and the mortality rates for people with genetic diseases increased from 2.2/100,000 in 1979 to 2.5/100,000 in 1992. The mortality rate was higher among men than among women and higher among blacks than among whites or other races for both birth defect- and genetic disease-associated deaths. The rate among infants with birth defects was more than 25 times higher than that among other age groups. About half of the children whose deaths were associated with birth defects had cardiovascular system defects, 15% had central nervous system defects, and 12% had chromosomal defects. For deaths associated with genetic diseases, hereditary neurologic or storage disorders were the most common genetic diseases (38%), followed by metabolic disorders (21%), sickle cell and thalassemia (12%). The decline in the rate of mortality from birth defects in the United States probably reflects improvements in medical and surgical care and other factors. Most of the mortality associated with birth defects remains in the pediatric age group (less than 15 years old). The upward trend we detected for the deaths with genetic diseases was most likely related to improved recognition and reporting of some genetic diseases rather than to the increased prevalence.