OBJECTIVES: To characterize availability of fever and malaria medicines within the retail sector in rural Tanzania, assess the likely public health implications, and identify opportunities for policy interventions to increase the coverage of effective treatment. METHODS: A census of retailers selling drugs was undertaken in the areas under demographic surveillance in four Tanzanian districts, using a structured questionnaire. RESULTS: Drugs were stocked by two types of retailer: a large number of general retailers (n = 675) and a relatively small number of drug shops (n = 43). Almost all outlets stocked antipyretics/painkillers. One-third of general retailers stocking drugs had antimalarials, usually chloroquine alone. Almost all drug shops stocked antimalarials (98%): nearly all had chloroquine, 42% stocked quinine, 37% sulphadoxine-pyrimethamine and 30% amodiaquine. A large number of antimalarial brands were available. Population ratios indicate the relative accessibility of retail drug providers compared with health facilities. Drug shop staff generally travelled long distances to buy from drugs wholesalers or pharmacies. General retailers bought mainly from local general wholesalers, with a few general wholesalers accounting for a high proportion of all sources cited. CONCLUSIONS: Drugs were widely available from a large number of retail outlets. Potential negative implications include provision of ineffective drugs, confusion over brand names, uncontrolled use of antimalarials, and the availability of components of potential combination therapy regimens as monotherapies. On the other hand, this active and highly accessible retail market provides opportunities for improving the coverage of effective antimalarial treatment. Interventions targeted at all drug retailers are likely to be costly to deliver and difficult to sustain, but two promising points for targeted intervention are drug shops and selected general wholesalers. Retail quality may also be improved through consumer education, and modification of the chemical quality, packaging and price of products entering the retail distribution chain.