Media literacy is one of the crucial human abilities in contemporary society. Media information knowledge is one of its key aspects. In this paper the authors operationally define the concept of media information knowledge and its relationship to the concepts of general education, general culture knowledge and general information knowledge. Furthermore, this paper analyses methodological problems of media information knowledge, i.e. construction and validation of testing instruments for media information knowledge. Based on the sample of 388 candidates for the graduate study of journalism, the following items have been analysed: the level of media information knowledge according to various knowledge areas; the metric characteristics and the relationship of the media information knowledge test with several correlates: gender, average grade during the study, test of professional journalists’ knowledge, vocabulary and foreign expressions knowledge, and orthography and grammar knowledge. Higher results in the media information knowledge test are related to better results in the professional journalists’ knowledge test, as well as with some aspects of general education, i.e. vocabulary and foreign expressions knowledge. It has also been found that male respondents have accomplished higher results in media information knowledge. A low correlation has been found with the average undergraduate study grade, while there is no relation of media information knowledge to orthography and grammar knowledge.