Air pollution from automobile exhaust and vehicular traffic density has become a serious problem particularly in metropolitan cities in India. The contribution of air pollution in urban areas can be calculated based upon the dispersion and distribution of traffic and population. Epidemiological studies have shown that the particulate air pollution is associated with the exacerbation of illness and number of deaths from respiratory and cardiovascular diseases (1). Vehicular pollution is also considered as a causative factor for increased incidences of allergic diseases (such as asthma), lung cancer, morbidity of rhinitis, pharyngitis, trachoma syndrome, neurasthenia, joint pains and disorders of digestive system (2). In addition, polycyclic aromatic hydrocarbons are the major air pollutants of automobile exhaust and were found to be mutagenic and/or carcinogenic in bacteria and mammalian systems (3,4). Earlier studies have also demonstrated that automobile exhaust can induce gene mutations, chromosomal aberrations, sister chromatid exchanges, micronuclei and cell transformation (5-7). Since some mutagens and carcinogens are found in automobile exhaust, their genotoxic effects on exposed population need to be evaluated. Hence the present study was undertaken to evaluate the cytogenetic damage in traffic policemen in Hyderabad. The twin cities Hyderabad and Secunderabad are located in the Central Deccan Plateau of India covering an area of 217sq Km. According to the pollution monitoring data the total vehicular pollution load in Hyderabad was calculated as 528 tonnes/day (t/day) during the year 1991-1992, 673.3 t/day during 20002001 and was increased to 1246 t/day in 2006 (8). This indicates a drastic increase of pollution in the city in recent years. Based on the pollution monitoring data from Andhra Pradesh Pollution Control Board8, highly polluted areas including Punjagutta, Abids, Charminar, Paradise and Ameerpet junctions in the city were selected for the study.