The aim of this study was to evaluate whether traffic police officers exposed to chemical, physical and psycho-social stressors, are at risk for alterations in plasma levels of prolactin (PRL) compared to a control group. Plasma PRL levels were evaluated in 92 male and 51 female, non-smoker, traffic police officers exposed to urban stressors and in 92 male and 51 female controls, matched by sex, age and working life (mean, SD and distribution), after excluding workers with the principal extra-occupational confounding factors. Mean PRL levels were significantly higher than controls in non-smoker, male and female traffic police officers (respectively, p=0.000 and p=0.013). The number of non-smoker, male and female traffic police officers with PRL values outside the upper normal limit for our laboratory was higher than, but not significantly different from controls. Mean PRL levels were not significantly higher than controls in smoker, male and female traffic police officers. The number of smoker, male and female traffic police officers with PRL values outside the normal limit for our laboratory was not significantly different from controls. The results suggest that exposure to urban chemical and physical stressors, interacting with psychosocial factors, may have an influence on PRL levels in traffic police officers. The level of plasma PRL might be a useful early biological marker for workers exposed to urban stressors.