All forms of life are unavoidably exposed to radiation from natural sources. Over the past decade, a growing awareness with regard to potential hazard incurred at work as a consequence of thisnatural radioactivity has emerged. Considering that this exposure should reasonably be regarded in certain circumstances as being the responsibility of operating management, the Internalcommission on radiological protection (ICRP) provided some practical guidance on good practices in this field in its recent publications. One key question however remains to identify properly thesituations in which exposure from natural sources should be included as part of occupational exposure and possibly subject to the same degree of control as those from artificial radiation sources.This paper intends to assess the scope of the problem and to review recent data reported on exposure which may occur in different workplaces due to natural sources: radon, material withelevated levels of natural radionuclides and cosmic radiation.