The article under review deals with innovative heuristic diagnostics approach to higher school studies. Today in Ukraine highly qualified multidisciplinary professionals with knowledge of foreign languages, ready to accept new and progressive trends and to participate in international cooperation and the formation of new attitude to Ukraine in Europe and worldwide are needed. An important role in the formation and training of such professionals belongs to pedagogical diagnostics. Quality performed diagnostic procedures require adequate criteria for measuring personal progress made by students in the creation of meaningful educational products. Our experimental work was carried out at Sumy National Agrarian University. The main focus of our experiment was aimed to determine the development of students’ theoretical knowledge of the subject «Professional direction of foreign language skills». The aim of this course, according to the State standard of teaching foreign languages, is mastering practical knowledge of speech units and theoretical knowledge of the rules of their formation, theoretical knowledge of the language system, i.e. lexical, grammatical, phonological and orthographic competences, country study knowledge. We have defined four levels of development and gave their characteristics. At the elementary level, students were limited to memorization and repetition of material from the textbook and implementation of relatively complex but common tasks. The second level – reproductive is shown by attempts of theory elements interpretation. Third level is characterized by the application of assimilated knowledge. The criteria for forming the fourth, heuristic, level of learning is the availability of theoretical understanding of principles and the ability to create students’ own theoretical knowledge. Levels of development of theoretical knowledge by students at every stage of learning correspond to the content of the subject and to the recommendations of the Council of Europe obtained to establish the State standard of teaching foreign languages in Ukraine. After the series of heuristic lessons control group of students were asked to write an essay to identify the level of development of theoretical knowledge. We have identified the following criteria: volume of written work, appearance and structure, comprehensiveness of content, lexical richness, grammatical competence development level. Our experiment results showed constant tends to increase the level of development of theoretical knowledge of the experimental group comparing to the relatively minor changes in the control groups. Thus heuristic learning diagnostics tools are used for increasing academic motivation and encouraging future professionals to efficient creative study comprehension.