Many previous researchers found that senior high school students in Indonesia commit errors in their writings. However, none focused on a class intended to smart students. It is important to discover what kind of errors they conduct the most. The goal of this study is to find out the dominant errors made by the student of Kelas Akselerasi (class for high-achieving students). The data were taken from the teacher collection of students’ writings. The writer used qualitative way where errors conducted by the students are described. The Error Analysis (EA) procedures were used to analyze the students’ errors. The errors were classified into omission, addition, misformation, and misordering which is based on surface strategy taxonomy. The findings show that the students made errors in all types. The most dominant error was omission (61.04%), followed by misformation (18.78%), addition (16.85%), and misordering (3.31%). Based on the causes of errors made by the students, the result shows that intralingual factor is considered the most dominant factor over interlingual tranfer. In conclusion, the students of Kelas Akselerasi still have serious problems in term of grammatical aspects even though they are considered high-achieving students in their school. Therefore, the writer recommends that the teacher make more efforts to minimize students’ errors