Integrated marketing communications as perspective on communication planning has increased its importance in the last decades. Based on theory, integration of communications implies four levels – company’s mission and brand proposition represent a higher level of integration while campaign messages and operative execution of the campaign represent a lower level of integration. Yet, even though integrated marketing communications are recognized as a relevant approach to communication planning, there is a lack of analysis on actual implementation of this concept in praxis. The purpose of my dissertation was therefore to study to what extent and how various levels of message integration are implemented in the company’s communications. For my own study, the tool for systematic analysis of integrated marketing communications was developed first to analyze key messages and visual emphases of communication campaigns. Then, two case studies were executed using a mix of qualitative and quantitative research approach. Two large Slovenian companies focusing on building corporate brands and successfully communicating with end users were selected. The chosen companies are Telekom Slovenije (with its communication campaign Modri svet) and A1 (with its communication campaign Lahkonočnice). Essential findings of my study show high integration of both communication campaigns. Besides, I can conclude that a higher-level integration does not result in lesser congruity but in more implicit and indirect links among communication meanings. One of the key contributions of my study was the development of a tool for systematic analysis of integrated marketing communications.