The study focuses on the impact of error analysis in the writing courses at tertiary level among non-English majors. In Bangladesh, the students of the non-English majors learn to write English through various writing courses. However, their proficiency in writing English is far from being satisfactory. Even after the completion of different language courses similar to English Fundamentals, Composition or other academic writing courses, they end up making numerous errors. In this research, the researcher endeavored to analyze the errors made by different nondepartment majors to discover the roots of errors and also to understand the difficulties students face while avoiding errors. The research was conducted through sample studies and interview questions. For the study 100writing samples were collected from tertiary level students from the renowned private universities in the country. The interview parts in this research reveal the real perspective of students regarding this issue. This research will help the teachers in figuring out why and how the errors occurred and in what ways they can be resolved. The researcher used both qualitative and quantitative data for analysis. The result of the findings has been analyzed and some suggestions have been given on the basis of the research.