Without an operative Birth Defects Registry, the state of Kentucky does not have a means of determining which of the nearly 6,000 syndromes and birth defects are the most common or the most rare, nor is there an ability to compare and contrast these data with data from other states. The authors reviewed 4,212 charts of patients evaluated between July 1981 and February 1995 by the Division of Genetics and Dysmorphology at the University of Kentucky Chandler Medical Center. Each patient's chart was categorized by diagnosis, and tables were generated to determine the most common diagnoses in the following groups: (1) multiple congenital anomaly syndromes, (2) teratogenic embryopathies, (3) chromosome anomalies, (4) isolated malformations, and (5) bone dysplasias. The most common multiple congenital anomaly syndromes were Down syndrome, Marfan syndrome, and trisomy 18. Fetal alcohol syndrome and infants of diabetic mothers were the most common embryopathies. Spina bifida (meningocele and myelomeningocele) was by far the most common isolated birth defect, followed by cleft lip/ palate and microcephaly. Achondroplasia was the most common bone dysplasia. These data support a number of previous assumptions including the universally high frequency of syndromes like Down syndrome and trisomy 18. The data also give credence to what was previously thought, but unproven, to be a high incidence of diabetic and alcohol embryopathies. The latter (fetal alcohol syndrome) has increased in frequency tremendously over the past 7 years. This is undoubtedly due in part to the overall increased awareness of the diagnosis in the medical community. However, it may also be due to the increased use of alcohol among Kentucky women. Other "rare" disorders, like diastrophic dysplasia, seem to be unusually the diagnosis in the medical community. However, it may also be due to the increased use of alcohol among Kentucky women. Other "rare" disorders, like diastrophic dysplasia, seem to be unusually the diagnosis in the medical community. However, it may also be due to the increased use of alcohol among Kentucky women. Other "rare" disorders, like diastrophic dysplasia, seem to be unusually