Irrational prescribing is a global problem. Rational prescribing cannot be defined without a method of measurement and a reference standard. The former is now available but the latter needs further development. Proven effective interventions to promote rational prescribing in developed countries are treatment protocols based on wide consultation and consensus, properly introduced and with a possibility of feedback; face-to-face education focussed on a particular prescribing problem in selected individuals; structured order forms; and focussed educational campaigns. Essential drugs lists are probably effective when based on consensus and used within a comprehensive educational programme. Printed materials alone are not effective. In most cases the usefulness of such strategies in developing countries has not been proven and should be studied. Medical education in clinical pharmacology and pharmacotherapy should be based on the practical needs of future prescribes, should include the principles of rational therapeutics and problem solving, and should immunize the students against the influences they are likely to encounter in their professional life, such as patient pressure, drug promotion and irrational prescribing by peers. Within the scope of a national formulary, specialist departments in teaching hospitals should define prescribing policies as the basis for prescribing, teaching, examinations and medical audit.