The experiences of NIOSH as pertaining to surveillance studies, descriptive studies and industrywide studies on the outcomes of pregnancies among workers were reviewed. Problems which come to the surface in such studies include inappropriate sample size, referent availability, exposure and outcome validation, tracing, analytical methods, and cost factors. Even so, much has been learned in the past decade regarding understanding and overcoming the methodologic and pragmatic difficulties in conducting occupational reproductive research. Surveillance efforts mainly have focused upon gathering and improving available data. Much effort has been spent in encouraging collection and recording of industry and occupation information on state vital records. In addition to improving available data, attempts have been made to analyze data from national and regional data bases to generate hypotheses regarding reproductive hazards. The second area of study, Health Hazard Evaluations, received about 500 requests each year for studies at workplaces. About 1 percent of the requests concerned reproductive hazards. The most common area of concern has been miscarriage, but requests have also been received to investigate birth defects, infertility, impotence, and hormonal issues. Epidemiological studies have been conducted as part of the Industrywide Studies program concerning pregnancy outcomes for workers exposed to vinyl- chloride (75014), polychlorinated-biphenyls (1336363), uranium (7440611), lead (7439921), carbon-disulfide (75150), cytotoxic drugs, and dioxin (1746016), and operators of video display terminals.