This study describes the results of a comparison of ambulatory medical care data for France, the Federal Republic of Germany (FRG), and the United States of America (U.S.). Data for this comparison were derived from independent national sample surveys in ambulatory care systems of the three countries in 1981-83. The French data set resulted from a sample of physicians who had been asked to document all patient-physician contacts for a specified 3-day period during 1982-83. The FRG survey of patient-physician contacts was performed in the fourth quarter of 1981 and the first quarter of 1982. Sample physicians reported for a sample of patient-physician contacts during two consecutive weekdays, the reporting periods being spread across the two calendar quarters in a balanced fashion. Survey physicians had been drawn at random from almost all ambulatory care specialties. U.S. survey data were obtained through a random sample of physicians reporting for a sample of their patient-physician contacts for a whole week, with the reporting weeks being spread across the whole year of 1981. Because regular office hours generally do not take place on weekends, Sundays were excluded in the French survey; in the FRG survey Saturdays and Sundays were excluded as reporting days. Although the French and the U.S. study universes consisted of almost all physicians practicing ambulatory medical care in the respective countries, the FRG physicians were drawn from five regions of the country systematically selected to represent the Federal Republic of Germany with respect to demographic population characteristics and physician specialty distribution. The universes of physicians and patient-physician encounters of the three national studies varied according to the ambulatory medical care systems of the respective countries. Data sets for this international comparison were derived from the respective national studies by selecting personal patient-physician contacts (in the physician's office or in the patient's home--referred to as "encounters") with eight physician specialties (general practitioners, pediatricians, obstetricians/gynecologists, internists, psychiatrists/neurologists, dermatologists, ophthalmologists, and otorhinolaryngologists). Patient variables used in the international comparison are patient age, sex, visit status, reason for encounter, and disposition. Yearly rates of personal patient-physician encounters in ambulatory medical care were estimated. Crude and age-sex standardized rates were computed for selected patient and physician characteristics.