Surveillance of drug consumption and disease incidence from medical relief missions in two locations--southeast Asia and eastern Africa--revealed close similarities. Analgesics, antibiotics, antimalarials, antihistamine or decongestant preparations (or both), bronchodilators, and scabicides were the 10 most commonly used drugs. Orthopedic, respiratory, gastrointestinal, dermatologic, and ophthalmic conditions, malaria, sexually transmitted diseases, and parasitic infestations were encountered most frequently. Recognition and early treatment of xerophthalmia, trachoma, and onchocerciasis, which are rare in more developed countries but common at tropical latitudes, can prevent the blindness that results from untreated disease progression. Pulse-temperature relationships and fever patterns may offer diagnostic clues to physicians deprived of laboratory support. Important logistic considerations, disease incidences, and selected topics and idiosyncrasies of humanitarian aid missions to tropical communities are discussed in hopes of aiding providers who are planning future relief missions.