Writing academic texts in English is an inevitable part of work of all academics and researchers. It is, however, often the case that scientifically excellent contributions are not published because of the lack of accuracy. Moreover, mistakes seem to be universal, articles being among the most frequent ones. This paper pursues the following aims: 1) systematically describe and categorize the use of articles in academic texts, 2) determine the most common mistakes in the use of articles made by L1 Czech writers, and 3) delimitate the problem areas and possible remedial steps. Four thousand and forty eight articles have been excerpted from six scientific texts in American English, classified and analyzed. Mistakes have been studied on scientific articles written by Ph.D. students with the conclusion that they can generally be classified into three areas. These areas should then logically represent the focus of instruction.