This review summarises the current database on the micronucleus (MN) assay with exfoliated cells (MEC assay) and evaluates the predictive value of this model for the detection of human cancer risks. The MEC test is a cost effective, non-invasive method, in which the formation of MN in exfoliated cells from different organs, such as oral and nasal cavity, bladder, cervix, and oesophagus is used as an endpoint to detect endogenous, lifestyle, occupational and environmental exposures to genotoxins as well as chemoprotection of various compounds in intervention studies. The results suggest that the MN assay might be a useful approach to identify antimutagens which are protective in humans. Based on the comparison of the data from MN experiments with results from epidemiological cancer studies, we conclude that the MEC assay is a useful biomarker for the detection of human cancer risk in organs to which the MEC test can be applied. However, the current data base is not sufficient to draw a firm conclusion on the specificity of this approach.