The purpose of this study was to analyze students` concepts in different test conditions about mechanisms of evolution. The tests were carried out in the low-and high-stakes test condition intended the 28 ninth graders. For this study, a questionnaire to investigate students` conception about evolutionary mechanism were selected and modified to paralleled test forms. MATE test to measure conceptual acceptance for evolution theory was applied. The research subjects are divided into two groups randomly, paralleled tests were administered to both groups. Based on the consistency and scores of answers, 16 interviewees were selected. The results of analysis of the students conceptions about evolutionary mechanism showed that the test score performed in high-stakes condition was higher than that performed in low-stakes condition. The patterns of answers by interviewees were divided into four types: scientific theorists, misconceptionists, conceptional confusers, and pragmatist. First three types were not related with test condition; however, the pragmatists answered with the same pattern as scientific theorists in high-stake test condition but they did differently at the lowstake test condition. These result is meaningful as that test condition might influence answers responded by students about evolutionary mechanism. Therefore, test conditions have to be considered as one of the factors when tests will be administered for students to identify students` real conceptions about evolution.