Introduction: Neopterin concentrations in body fluids can be regarded as an indirect estimate of the degree of oxidative stress emerging during cell-mediated immune response thus elevated levels were observed in silicotic individuals. Aim of work: to study the neopterin levels among workers exposed to marble dust, and to assess the use of neopterin versus oxidative stress indicators as a screening tool for silica exposure and/or effect. Materials and Methods: The study was performed on 48 workers. They were divided into 24 workers exposed to marble dust compared to 24 non-exposed subjects as a control group. The studied group was subjected to a questionnaire, clinical examination, and laboratory investigations including neopterin levels in urine and oxidative stress indicators (malondialdehyde MDA, and total sulfhydryl group SH) in urine. Environmental measurements of air in the workplaces were done. Results: Comparison of neopterin levels between the studied groups revealed an elevated mean level among exposed group with a highly significant statistical difference at p-value < 0.001. As regards MDA, an elevated mean level in the exposed group with a highly statistically significant difference was found, while SH showed a decreased mean level in the exposed group in relation to the control with a non-significant statistical difference. Comparison in-between the biological parameters in urine, among exposed group, revealed a positive correlation of neopterin versus MDA levels, as well as a negative correlation of SH levels versus both neopterin and MDA levels. All correlations proved to be statistically non- significant. Conclusion: Neopterin levels in urine increase significantly in workers exposed to marble dust suggesting its use as a simple non-invasive quantitative biological indicator for exposure and effect.