Reasoning is an indispensable ability of learners in physics learning as it is related to the learning outcomes achieved. This study aims to obtain a picture of scientific reasoning in 231 high school students in Palembang City in academic year 2017/2018. The type of this research is descriptive research with survey method. The ability of scientific reasoning and mastery of the physics concepts of students was obtained through written test in the form of multiple choice reasons. Problems used in the study contained 18 items with details of 12 questions about scientific reasoning and 6 questions about mastery of physics concepts. The result of the research shows the scientific reasoning ability of high school students was in the low category and the mastery of physics concept of students remained in the medium category.