This thesis describes architectural patterns MVVM, MVP and MVC, and then using these patterns I have implemented three functionally equal Windows phone applications. On these three sample applications I have added new funkcionalities, specifically changed the way of saving data from a local database to work with the database on the server. The application was built using the model Firma. The application is used to add, modify and monitor partners and to add their documents and their sub items. The application is designed for the Windows Phone 7.5 platform using WindowsPhone SDK7.1 and the programming language C #. These three applications indicate that it is possible to build applications in all three patterns. Before making the first application, the pattern that seemed the easiest to implement was MVVM. One of the main reasons is that it is designed specifically for Microsoft application development for WPF, Silverlight and Windows phone. The reason for the comparison was that other patterns, especially MVC, are more widespread than MVVM, and are much more familiar to developers. Although I also started the development process with only the knowledge of the MVC architecture pattern it has not been a problem for me. Switch to other architectures was easy because of their similarity, especially that two of the three components are fairly equal, the Model and the View. Model is the same in all architectures while the View component was changed. While developing these applications I have come to the conclusion that the MVVM is well-conceived and will very likely be the best pattern for development when Microsoft improves it. Specifically, when it is fully adapted to the Windows phone platform. Linking data across with binding's makes very simple code that should eventually be firmly separated, but at the end did not turn out like this because of a flaw in the platform. Problems arose when connecting the some components which could not be binded. This problem will probably be fixed in newer versions of the platform. To those who are eager to engage in the development of Windows phone applications I recommend the MVVM pattern.