Inappropriate drug use is a serious problem in the control of diarrhoeal diseases. To address this problem, the World Health Organization's Programme for the Control of Diarrhoeal Diseases reviewed the literature on the most commonly used antidiarrhoeal agents, and distributed the resulting document widely in 1990. Antidiarrhoeal drugs received simultaneous attention in the popular media as groups and individuals campaigned against their registration and use. This article evaluates the actions against antidiarrhoeal drugs taken by national drug regulators in the period during and after these events (January 1989 until December 1993). Information on regulatory actions was requested from countries and extracted from published and unpublished sources. Sixteen countries reported regulatory actions on 21 occasions during the period of study. The majority of actions concerned antimotility drugs; few were against adsorbents, antidiarrhoeal drugs containing antimicrobials, or adult formulae. Six countries took action against large and heterogenous groups of antidiarrhoeal drugs. Most actions occurred in the two-year period immediately following the distribution of the WHO review and the attention in the media. The sequence of distribution of the review, media coverage, and activities of dedicated groups and individuals, followed by a noticeable cluster of regulatory actions suggests a clear relationship. Further research is necessary to determine the relative role of each activity. There are several constraints to deregistration of profitable drugs and some drug regulators may have chosen to delay action until the end of the drug's registration cycle. Many more antidiarrhoeal drugs may lose their register in the future through a passive deregistration process. Deregistration of inappropriate drugs will probably take much time and widespread deregistrations are not likely. Furthermore, regulatory actions alone are probably insufficient to achieve a more appropriate use of drugs. More effect can be expected from simultaneous regulatory, managerial, and educational interventions directed at providers, combined with communication to the general public.