Sir,We read with interest the article by Şenel et al., who compared mean platelet volume (MPV) in recurrent aphthous stomatitis and Behçet's disease. They conclude that MPV levels could not be used as an indicator or a diagnostic marker for the patients with Behçet's disease and recurrent aphthous stomatitis.[1] However, there are major problems in this study:This study has no exclusion criteria. However, there are many diseases and medications affecting MPV levels[2]In this study, MPV measurement technique is not written. Preanalytical variables, such as the anticoagulant used, and the time between blood collection and measurement are known to significantly affect MPV measurements. Although ethylenediaminetetraacetic acid (EDTA) is traditionally used and recommended for samples destined for blood counting, it is well known that platelets collected into EDTA anticoagulants undergo time-dependent platelet swelling and activation.[34] What were made in order the platelet swelling induced by EDTA?What are the date ranges of this study? Because recent studies have shown seasonal changes in MPV levels.[5]There are three groups in this study. For this reason, analysis of variance test (including post hoc) should be applied in statistical analysisThis study is retrospective. One of the main limitation of this study is that analysis was based on a simple baseline determination that may not reflect in patient's status over long period (should be written “Discussion-limitations” section).