Determining real contact area is a big problem in engineering, since, in general the contact conditions are calculated with the assumption of nominal contact area in the contact, which is greater than the actual. Taking this into account leads to the calculation of milder conditions in contact and thus to the actual construction of engineering applications. In this diploma thesis we researched the influence of different material properties on the deformation of the real contact area. The results showed that the real contact area is affected by different mechanical, as well as different topographic properties. In addition, the contact conditions are also affected by the geometric changes of contacting asperities. The obtained experimental results were compared with one statistical and two deterministic approaches, which are used to predict behaviour in contact. Each theoretical approach has its advantages and disadvantages. The main disadvantage are the assumptions, that lead to large deviations compared to the behaviour in actual contacts.