The provision of essential drugs and the involvement of various potential and existing health care providers (e.g. teachers and traditional healers) are two important primary health care strategies. One local group that is already actively supplying the medication needs of the community is the patent medicine vendors (PMVs), but the formal health establishment often views their activities with alarm. One way to improve the quality of the PMVs' contribution to primary care is through training, since no formal course is required of them before they are issued a license by government. Primary care training was offered to the 49 members of the Patent Medicine Sellers Association of Igbo-Ora, a small town in western Nigeria. Baseline information was gathered through interview, observation and pre-test. A training committee of Association members helped prioritize training needs and manage training logistics. Thirty-seven members and their apprentices underwent the 8 weekly 2-hr sessions on recognition and treatment (including non-drug therapies) for malaria, diarrhoea, guinea worm, sexually transmitted diseases, respiratory infections, and malnutrition, plus sessions on reading doctor's prescriptions and medication counseling. The group scored significantly higher at post-test and also showed significant gains over a control group of PMVs from another town in the district. The Igbo-Ora experience shows that PMVs can improve their health care knowledge and thus increase their potential value as primary health care team members.