Needless to say, the dissemination of knowledge in the global scale is dependent upon translation, i.e. translating a text from the source language to the target language, English here as being widely considered the lingua franca of science and technology. Nevertheless, in spite of its crucial role, there seems to be some constraints on the way to an intelligible work of translation, one of which could be not being competent in the grammar of the target language. Otherwise stated, familiarity with the grammar of the target language, English here, seems to be of paramount importance for the incompetence could obviously hinder the comprehensibility of written works in general, and scientific research articles in particular. In this respect, we should hasten to add that the translation of scientific research articles from Farsi into English is not an exception. Being the focus of deep concerns in Iran, this paper concentrates on the linguistic analysis of mistranslations of two research articles which were written by students of post graduate courses of mechanical engineering, and physics in Iran, both of which required revision for conspicuous grammatical errors, and as a result, unintelligibility. The analysis reveals the crucial role of grammatical competence for Iranian students in higher education in order to help them find their deserved stance in related international discourse communities.