Objective: There are still contradictory data in the literature whether patients with acromegaly are under risk interms of atherosclerotic heart disease. Increased arterial stiffness dev elops before atherosclerosis and is ev aluated to be a risk factor for atherosclerosis. Mean platelet v olume (MPV) is currently gaining interest as a new independent cardiov ascular risk factor. There are contrasting v iews about arterial stiffness in patients with acromegaly. There is no report in literature study ing MPV in acromegaly patients. The aim of this study was to ev aluate MPV and arterial stiffness in patients with acromegaly. Methods: This study was designed as an observ ational cross-sectional, casecontrolled study. Twenty -eight patients with acromegaly and 22 healthy v olunteers were recruited for the study. The arteriography dev ice Mobil-O-Graph® (IEM GmbH. Stolberg, Germany ) which can perform oscillometric measurements was used to measure arterial stiffness. The Mann-Whitney U test, Student's t-test, Spearman's nonparametric correlation analy sis and the chi-square test were used to statistical analy ze. Results: Aortic pulse wav e v elocity (PWV) v alue was found to be 6.41 ±2.1 2 m/s in the patient group with activ e acromegaly and 5.24±1.04 m/s in the healthy control group. The difference was statistically significant (p=0.03). The mean MPV v alue was found to be 9.68±1.1 1 in the patient group with activ e acromegaly and 8.53±1.1 8 in the healthy control group. There was a statistically significant difference between the two groups (p=0.004). In patients with acromegaly, a positiv e correlation was found between MPV and insulin-like growth hormone-I (IGF-1 ) lev el (p=0.021, r=0.434). Conclusion: We determined an increase in aortic PWV and MPV in patients with acromegaly. In conclusion, ev aluation of MPV and arterial stiffness in future studies could be beneficial in determining the risks for cardiov ascular disease in patients with acromegaly.