The Medical Genetics Unit at Universidad del Zulia (UGM-LUZ) gives counsel to patients with partial and total genetic diseases. Counseling is available for patients of both sexes and all ages, from public and private health centers and several medical specialities. In the present study an analysis of 4617 clinical records from families referred for genetic counseling to the UGM-LUZ is given. The study spans from January 1983 to December 1992. Fifty four (1.2%) of these histories correspond to pre-nuptial counseling, 773 (16.7%) pre-conceptional, 316 (6.8%) pre-natal and 3474 (75.3%) for diagnosis. A computerized system was developed, based on relational data base manager, that permits access with interactive Dbase type applications. A total of 5433 diagnoses were made. The most frequent causes of genetic diseases were chromosomal abnormalities (12.32%), mainly Down and Turner syndromes. Mendelian diseases occupied 14.45% of all cases, with Marfan and Noonan syndrome, Osteogenesis imperfecta. Duchenne-Becker muscular dystrophy and Incontinentia Pigmenti as the most frequent syndromes. Diseases that involve multifactorial inheritance, such as neural tube defects, accounted for 7.36% of all diagnosis. Effects of teratogenic agents such as german measles, radiations and others were detected in 3.96% of all cases. In 8.5% of the patients a hereditary factor was suspected. No definitive diagnosis was reached in 32.45% of all cases and 20.96% of the patients were normal. The need for data from other medical genetic centers is stressed. In this way the regional and national genetic diseases on morbidity can be known.