The aim of this study is to determine the students' misconceptions about the digestive system. In this quantitative research, the study group comprised totally 259 sixth-, seventh-, and eighth-grade students. The data were collected through a three-tier diagnostic test and analyzed in terms of scientific knowledge, the lucky guess, lack of knowledge, and misconception levels of students on digestive system. According to the findings, 20.1% of the students' answers were in the scientific knowledge category and 9.1% were in the lucky guess category. On the other hand, 39.7% of the answers were in the lack of knowledge category and 26.0% were in the misconception category. The most prominent findings in the study were the students' misconceptions in a few questions, especially about physical and chemical digestion. In addition, some students did not fully understand the distinction between the excretory and digestive organs and the functions of some accessory. They also gave incorrect answers about the organs where the digestion of proteins, carbohydrates and fats begins and ends. At the end of the study, suggestions were made to eliminate the misconceptions.