A 6-year experience with a center-satellite system for the provision of comprehensive genetic counseling services to a large geographical area is described. A series of 12 satellite genetic clinics established throughout northern and central California have brought genetic counseling services to within a 2-hour drive for most patients. These satellite clinics are largely organized by local groups (such as National Foundation-March of Dimes chapters and county health departments) but are backed by the personnel and resources of the center at the University of California, San Francisco. Assistance is generally provided by county public health nurses who collect medical records from referring physicians and pedigrees from the family. Specimens for cytogenetic or special biochemical studies are brought back to the center, but, if possible, other laboratory determinations, radiological investigations, and specialty consultations are obtained locally. Follow-up counseling may be provided by the public health nurses, and a written summary is sent to each patient or family. The socioeconomic spectrum of the patients seen at the satellite clinics is much broader than at the central clinic, and the establishment of a satellite clinic results in a great increase in the number of cases seen from the area in which it is located. Physician time per patient and cost of services per patient are substantially the same in both central and satellite clinics. Based on population figures applicable to the state of California, it is estimated that approximately 60-70 comprehensive counseling centers, each with up to 15 satellites, could adequately provide for the foreseeable genetic counseling needs of the United States.