Information regarding practice patterns specific to acquired immunodeficiency syndrome (AIDS) was obtained in 1988 from 1774 family physicians in California using a mail survey. Data were analyzed across the following county groupings: Los Angeles County, other counties in standard metropolitan statistical areas, and counties outside standard metropolitan statistical areas. Comparisons were made with the data from a telephone survey conducted in 1986. Differences over time were analyzed. By 1988, the percentage of physicians treating or referring patients for possible AIDS had more than doubled in counties outside standard metropolitan statistical areas. The percentage of physicians reporting one or more diagnosed cases of AIDS had tripled, a finding that suggests the importance of AIDS in family medicine is increasing at a rapid rate. In addition, survey results indicate that a majority of those surveyed still lack the AIDS-related knowledge and competency necessary to effectively deal with AIDS.