Reptilian species are potentially efficient bioindicators of pollution and habitat destruction. Turtles may be especially useful for monitoring the chemical contamination of their habitats. The aim of this study was to assess the genotoxic effect of environmental pollutants on Balkan pond turtle Mauremys rivulata (Valenciennes, 1833) from the Biga Streamp Canakkale, Turkey. Healthy mature animals were collected using the hand-capture method from four stations: estuary zone, city centre, buffer zone and industrial zone of the stream. Blood samples of live specimens were obtained in within one day of their capture. The peripheral blood smears for each specimen were prepared, fixed with methanol for 15 min and dyed with Giemsa stain. Micronuclei and other nuclear abnormalities such as blebbed, kidney-shaped, lobed and notched nuclei were identified. Comparing the nuclear abnormalities in the samples, it was determined that their frequency was highest in the samples collected from the station in the city centre (9.16 +/- 0.02). The results indicated that the levels of genotoxic pollutants in different regions of the Biga Stream lead to DNA damage in Mauremys rivulata.