A study of prescribing pattern in tertiary, primary and urban general practice levels of the Indian health care delivery system was undertaken by analyzing 1810 prescriptions for 3932 drugs. The study evaluated feasibility of data acquisition methods and compared the prescribing frequency of various drug groups and of individual drugs in three commonly used categories. The mean number of drugs per prescription was highest in urban general practice (2.41). The four most frequently prescribed drug groups were antibacterials, vitamins, nonsteroidal antiinflammatory drugs (NSAIDs) and respiratory drugs. The study delineates the differences in prescribing frequency of drug groups and individual drugs across the three levels of health care and the results suggest intervention strategies to promote rational drug therapy.