Compared to the wide range of occupational exposure standards available in different countries for industrial chemicals, there are only a few similar standards set for pharmaceutical agents. These substances produce physiological effects in relatively small doses, and there are documented ill-effects from worker exposures, hence the need for such standards. There are different approaches to setting occupational exposure standards for pharmaceutical agents. One derived from the nuisance dust standard may be used, although that may not be wholly appropriate. An approach has been previously suggested for ethinyl estradiol, and this requires the minimal effective dose, a safety factor, an assumption of equal absorption by inhalation as by the oral route, and the volume of air inhaled over an 8-hour day. Toxicological and pharmacological information for zeranol, an animal growth promoter with estrogenic properties, is used with these criteria to obtain an airborne standard. It can be shown that depending on what assumptions are made, there can be more than a tenfold difference in standards reached. There are other difficulties with setting standards for pharmaceutical agents, depending on the group of substances involved. Airborne standards are useful for medicines that are inhaled. A "skin" notation may be needed for those that can be absorbed via the dermal route. Biological standards should also be considered. Provision of standards for pharmaceutical agents will go some way towards protecting exposed pharmaceutical workers.