OBJECTIVES To assess the quality of nurses' prescribing through an assessment of their prescription in relation to diagnosis, and to investigate trends in drug use in Botswana primary health care.

METHODS Key data regarding nurses' adherence to national prescription and treatment guidelines were obtained through participatory observation using a questionnaire, related to each consultation. Adherence was categorized into (i) Full adherence, (ii) acceptable adherence, (iii) acceptable adherence, but one or more useless, but not dangerous, drugs and (iv) insufficient or dangerous treatment. The study comprises data on nurses' prescriptions, diagnoses and quality of dispensing in 2994 consecutive consultations in 30 primary health care facilities in three districts of Botswana: Ngami East, Gaborone and Kgalagadi North.

RESULTS The average number of drugs prescribed per patient was 2.3. Antibiotics were prescribed in 27% of all encounters. Full adherence was found in 44%, acceptable compliance in 20%, `acceptable, but one or more useless, but not dangerous, drugs' in 33% and `insufficient or dangerous treatment' in 3% of the consultations. Four factors were found to be independently associated with full adherence: patient age 16–31 years, specified diagnosis, type of health facility and nurses' years of practice (4–11 years best).

CONCLUSION Although Botswana's health workers perform relatively well in terms of drug use indicators, there is a clear potential for improving health workers' adherence to national treatment guidelines.