The passing of regulations requiring periodic occupational hygiene monitoring surveys is one way of controlling workers' exposure to hazardous materials. The results of this study showed that this control is ineffective. The source of data was Occupational Hygiene Survey (OHS) records which were archived in the Institute for Occupational Health, Tel Aviv University and related only to workplaces that requested an OHS. The mean frequency of surveys carried out in the workplaces studied was significantly lower than the required one. Although the main factors required to ensure effective implementation of the regulations exist in Israel, i.e., monitoring services and enforcement authorities, excursions above permitted levels (overexposure) are still widely occurring. From all the measurements made over the study period (1989-1991) the ranges of overexposure were 31-75% for silica, 26-32% for talc, and 19-41% for lead. The results of the study highlighted the need to strengthen the authority of the bodies involved in occupational hygiene by increasing intervention. This could be achieved by enlarging the capabilities of the enforcement authorities by giving authority to occupational health physicians and to the organization carrying out the survey.