The main subject of this graduate thesis is analysis of usage of customer relationship management system on communication activities of the company. Primarily, it defines the concept of customer relationship and business strategy, as well as the importance of proper implementation of an information system that enables the proper introduction of the CRM - Customer Relationship Management. The customer relationship managemenet system indicates to all employees that the focus of the company is on customers. It also enables adjusting the relationship between the first line employee and the individual customer and it explains to which things and situations should be given more attention and which less while trying to make adjustments to the user. The importance of understanding and categorizing segments of existing customers in order to maximize their value for company while creating a loyal relationship is strongly highlighted in this graduate paper. The mentioned importance also implies satisfaction of existing customers and their resistance to services and products from the competition. For a proper understanding of the integration of the customer relationship management system and communication activities in the enterprise, it is necessary to first develop the concept and forms of communication, as well as the marketing communication interface of the company itself. Communication activities and customer relationship management system are analyzed on an example of company DM which, with its successful loyalty program, is among the largest drugstore chains in Europe. The loyalty program and customer relationship management system that the selected company applies is elaborated in details and based on critical review of author suggestions are provided for improving communication activities that include printed materials and leaflets that are sent via e-mails, SMS messages, network pages and mobile application of the company. Suggestions for improvement are based on the information the company receives from its loyalty program members and on which communication activities can be better tailored to each segment and customer profile in order to maintain a leading position on the market and to increase the market share of its existing customers.