Nowadays every company usually has more than one information system. Only few have thought about centralized identity management. Often every information system is keeping its own authorization and authentication database. That leads to a situation when one specific employee has a digital identity in every information system. That means that he has more than one login and password. Sometimes this information is kept on a list of paper, which threatens the security of company’s information systems. For example, if a person’s e-mail address changes this person has to make the changes in every information system. Moreover, often different information systems have to support user roles which have been assigned to the same people. These roles describe the same logical entity. When roles change, the changes have to be manually made in every information system. In this paper will show how to deal with this problem, how to implement unified identity with minimum changes in the existing information systems, and no harm to business processes. This paper delivers a methodology for implementing unified identity, without changing the existing identity management procedures. Bachelor thesis report contains 50 pages, 13 pictures, 4 tables. Bibliography includes 19 sources.