Background: This study aimed to compare the impact of midazolam, propofol, dexmedetomidine infusions for 24th hour on total antioxidant status (TAS), total oxidant status (TOS), oxidative stres index (OSI) and prolidase levels. Material and Method: 75 patient ICU patient who were mechanically ventilated enrolled to the study. Patients randomised to three groups. Group I (n=25, midazolam): 0.02 mg/ kg/h midazolam, Group II (n = 25, propofol): 1mg/kg/h propofol, Group III (n=25, dexmedetomidine): 0.2 µg/ kg/h dexmedetomidine infusions was started. Dosage were arrange to achieve Ramsay sedation score 3. Blood samples were collected in basal, 6.,12.,18., 24. hour, and hemodynamic parameters were also recorded in the same time intervals. Results: In midazolam group 24. hour TAS levels were significantly decreased and TOS, prolidase and OSI levels were significantly increased compared to the basal level (p0.05). Basal TAS, TOS, prolidase, OSI levels were not statistically significantly between the different groups (p>0.05).Conclusion: This study showed that there were no statistically significant differences between the groups. Among hemodynamic parameters Dexmedetomidine was found to be having statistically significant favorable results in comparison to others. However there results should be clinically and molecularity verified with large scale further studies.