Many studies have been done to document drug use patterns, and indicate that overprescribing, multi-drug prescribing, misuse of drugs, use of unnecessary expensive drugs and overuse of antibiotics and injections are the most common problems of irrational drug use by prescribers as well as consumers. Improving drug use would have important financial and public health benefits. Many efforts have been undertaken to improve drug use, but few evaluations have been done in this field. This article provides an overview of 50 intervention studies to improve drug use in developing countries. It highlights what type of interventions exist and what is known about their impact. It reveals that commonly used interventions, such as an essential drug list and standard treatment guidelines, have rarely been systematically evaluated so far. The majority of intervention studies are focused on prescribers in a public health setting, while irrational use of drugs is also widespread in the private sector. Furthermore, the magnitude of inappropriate drug use at community level is often overlooked and few interventions address drug use from a consumer's perspective. More research on different types of intervention strategies in various health care settings is needed to draw conclusions on the effectiveness of a specific intervention strategy. Also more research is needed on socio-cultural factors influencing the impact of drug use interventions, particularly from a user perspective. To enhance evaluative research, more technical support will be needed for researchers in developing countries. The design of available studies from developing countries is generally weak, only six of the 50 studies included in this overview were randomized controlled studies. In order to provide technical support and coordination of future intervention research the establishment of an international resource centre for drug use intervention research is recommended.