Background: DNA damage associated with passive smoking has been shown in children. Severe DNA damage can change the apoptosis process of the cell. M30 and M65 biomarkers are markers showing the apoptosis process and can be quantitatively measured. We aimed to determine M30 and M65 levels as apoptosis biomarkers in children exposed to passive smoking. Methods: A total of 79 children were included in the study. Urine cotinine level was measured with the chemiluminescence method and the levels of apoptosis biomarkers M30 and M65 were measured in peripheral venous blood with PEVIVA/ALEXIS ELISA kits. Results: The mean serum M30 level of the group exposed to smoking was found to be significantly low compared to that of the control group (p=0.01). The serum M65 value was not significant in either group (p=0.1). No correlation was determined between the mean cotinine level and M30 (r=0.25, p=0.02) or M65 (r=0.16, p=0.15). Conclusion: The results of this study showed that the apoptosis biomarker M30 levels of the children exposed to passive smoking were low compared to those of the control group which can be interpreted as apoptosis inhibition in exposure to cigarette smoke. Further clinical studies are needed.