The present study aimed at investigating the effect of using an ESP on-line course on developing reading comprehension skills. The target reading comprehension sub- skills were: Predicting, Making relationship, Identifying information, and Word Recognition. The researcher used the quasi-experimental design. The participants in the study included one experimental group (N=30) freshman students at the Faculty of Commerce, Mansoura University. The instruments used were ‘'Needs analysis questionnaire, reading comprehension skills questionnaire and a pre-post reading comprehension test''.  Validity and reliability were established before administering the pre-post reading comprehension test. The study was conducted during the first semester of the academic year 2017/2018.  Results showed that there was a statistically significant difference between the pre and post administrations of the reading comprehension test in favor of the posttest. Results indicated that an ESP program has an effective impact on developing reading comprehension skills for freshman students at the Faculty of Commerce, Mansoura University. Key words: ESP, E-learning, On-line course, Reading comprehension skills.