In the article the authors analyze a mistake as an integral part of any studying process on the example of studying English at University. The authors point out that making mistakes is quite natural, moreover it helps reveal major problems in terms of both studying and teaching. Thanks to students’ mistakes the teacher has an opportunity to understand how to work with a definite group, what aspects and methods need more attention and activity. The article considers basic reasons which lead to mistakes and ideas how to deal with them based on the authors’ experience. It is pointed out that the teacher has to decide how to prevent and work with mistakes in every occasion as every student and every lesson are unique and require individual approach and attention.