Objective:This study was performed to compare the effectiveness of anti-coagulation with ethylenediamine tetraacetic acid (EDTA) and citrate on mean platelet volume (MPV) measurement.Methods:EDTA and citrate-based anti-coagulant blood samples from the same patients were read in the auto-analyzer at 0, 30, 60, and 120 minutes after sampling and the results were compared.Results:A total of 54 patients, 29 of whom were women, over the age of 18 were included in the study. Baseline blood MPV values were found to be 0.524 fL greater in the EDTA-based group (p0.05). When the deltaMPV values of the EDTA and Citrate groups were compared, it was found that there was no difference at 30 and 60 minutes (p=0.531 and p=0.566, respectively). In addition, it was found that there was no significant difference between deltaMPV/platelet count ratios (deltaMPV/PC) in all time periods in the EDTA group (p>0.05) and there was a significant difference between all time periods in the citrate group (p<0.001).Conclusion:Results in the first hour were similar in both anticoagulation groups. However, additional increases were observed in each half-hour period in both groups. Making measurements of MPV within the first hour and in the same half-hour period minimizes the measurement errors that may occur. When EDTA is used as an anti-coagulant, it performs better than MPV due to the fact that there is no change in the MPV/PC ratio during the first two hours.