This research aimed to examine the difficulties and failures of eleventh-grade students regarding probability concepts. With this aim, ten different open-ended probability problems were asked to the 142 eleventh-grade students. Each of these problems requires using different basic probability concepts. It is qualitative research, and the data gathered in this study were analyzed using by descriptive analysis method. The findings indicated that many of these students had difficulties in solving probability problems and failed to apply different probability concepts to these problems. Notably, it was stated that many students had difficulties in finding all the probabilities without any missing in these problems. Besides, it is essential to develop reasoning skills since the students usually used trial-and-error method and prediction to solve probability problems.