In this work immunofluorescent antikinetochore (CREST) staining was used to analyse bone marrow micronuclei (MN) from free-living animals belonging to four different rodent species. Yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) were trapped in the Czech Republic, Algerian mice (Mus spretus) in Spain and house mice (Mus musculus domesticus) in Italy. Animals were collected in areas displaying low or high environmental pollution in order to investigate the sensitivity of CREST analysis on bone marrow MN as a biomarker of environmental stress in situ. Differences in total MN frequencies between animals collected in control or contaminated areas were statistically significant for two species, whereas the differences in CREST+ MN were statistically significant for three species. Interestingly, the percentages of CREST+ MN in animals collected in the control areas were very low (3. 2-8.7%), suggesting that activities inducing alterations in the distribution of chromosomes are very rare in natural conditions. The increased frequencies of CREST+ MN observed in areas with high environmental impact indicate that activities producing loss of chromosomes at mitosis may be characteristic of anthropogenic environments such as industrial settlements around petrochemical factories. Our data suggest that the analysis of CREST+ MN may represent a sensitive end-point for the detection of environmental contamination by genotoxic xenobiotics, offering the advantage of providing information on the mechanism of action of environmental contaminants.