The ability to publish research papers is a must for scientists nowadays. Ideally, at the very beginning of their career, young researchers, PhD students, should be instructed in writing research papers and should get feedback on their texts. In this study, the first manuscripts from 22 doctoral students, non-native English speakers, 223 pages were analysed for errors in grammar, spelling, punctuation, and style. For each type of error and each student, the average per page was calculated. The most frequent errors were identified in using articles, formal features, missing information, and the use of inappropriate words. Individual students showed significantly different levels, which reflected their previous language training and the approach (responsibility) to completing the task. The results will be used to modify the course in Academic Writing (more attention paid to the most frequent errors) and individual work with students. Keywords: academic writing, scientific writing, research paper, PhD student, error