Objectives: Exposure to cement dust can cause various occupational health problems due to its increasing incidence and long-term complications. However, the infl uence of cement dust on phagocytic function of polymorphonuclear neutrophils (PMNs), has not as yet been investigated. Therefore, the aim of the study was to measure the phagocytic activity of PMNs by assessing chemilumiscence (CL) response in cement mill workers and controls. Material and Methods: In this study, 50 volunteer males, aged 25-60 years, apparently healthy and nonsmoking, were randomly selected from among cement mill workers. These workers were further classifi ed into subgroups based on exposure duration of less than 10, 10-20, and more than 20 years. The controls were 50 healthy, nonsmoking, males who matched the study group with respect to age, height, weight, and socioeconomic status. The phagocytic function of PMNs, stimulated with opsonized zymosan, was determined by measuring CL response. Results: The fi ndings show a signifi cant decrease in phagocytic activity of PMNs [PMNs OPZ p < 0.005] in cement mill workers compared to controls. Conclusion: It is concluded that exposure to cement dust can impair the phagocytic function of PMNs which is refl ected in decreased chemiluminescence response.