The aim of the study is to evaluate the competencies of middle school teachers in preparing openended items used in in-classroom assessment by examining the theoretical knowledge for writing openended items and the items they prepared. The study was conducted as a survey research with quantitive approach. The sample of the study is consisted of 167 teachers. To define participants, maximum variation sampling has been used. The data were collected by the questionnarie called “Information Form for Preparing Open-Ended Question” developed by the researchers. Percentage and frequency distributions, chi-square test of independence and document analysis were used in the analysis of the data. According to the findings of the study, it has been found that the criteria holding the highest competency level is “considering the appropriateness of the items with age and grade” with the rate 31,7%. Among determined 18 criteria, there found a relationship between the teacher competencies related with the criteria “considering the appropriateness of the items with age and grade” and both gender and school type. It has been concluded that the tests including open-ended items are commonly used for in-classroom assessment but the teachers are generally quite inadequte competency in preparing these items.