BACKGROUND African Medical and Research Foundation (AMREF) has for forty years offered airborne specialist surgeons or surgical teams to supplement the major surgery conducted by local hospital staff, particularly in Kenya and Tanzania. OBJECTIVE To quantify and qualitatively describe the contribution of airborne surgical outreach services in relation to the total surgical output of remote rural hospitals in Kenya and Tanzania. DATA SOURCES Surgical theatre registration books of one government and two church/mission owned hospitals in Kenya and Tanzania from 1994 to 1995; and service records kept by the surgeons during outreach trips in the same period. RESULTS AMREF contributed 15.1% of all major operations, and operations performed by AMREF were relatively complex. The average number of AMREF's major operations performed per visit was 17 and per visit day 4.3. Numerous minor operations and examinations, ward rounds and an average of 10 patient consultations per day were done during the visits. CONCLUSIONS Total population-based operation rates, and rates by sex and age, are useful indicators for monitoring and comparison. Every hospital should report, annually, major operations performed by type and by age and sex of patients, with special mention of operations and consultations performed by visiting teams, if any. Each hospital should also state the estimated population of its current catchment area.