In the present study, the micronucleus test was applied in exfoliated cells of buccal mucosa to assess the mutagenicity risk associated with occupational exposure for gas station attendants. For each individual, 2000 exfoliated buccal cells were analyzed for micronucleus frequency. A highly significant difference was found between exposed and control groups. Likewise, a significant difference was found between these groups regarding the frequency of binucleated and broken egg cells. To determine whether smoking, alcohol habit, age, gender, or working time could exert any additional effect, we determined the frequency of micronuclei and binucleated and broken egg cells amongst exposed and control individuals. The results allowed us to conclude that the individuals studied belong to a risk group and should periodically undergo biological monitoring and appropriate care.