This paper reports a study in how interaction design and graphic design is affected in the process of developing an mobile application to complement the use of an existing webbsite. The paper also ask how developers are affected in this process by the use of designpatterns. The purpous of the report was to see how designpatterns affects the development of mobile applications and how the interaction and graphic design differs between various company webbsites and their related application. A study was conducted by comparing three diffrent webbsites with three related applications to find material for our thesis. Interviews were conducted on three diffrent companys that work professionaly with creating mobile applications. The results show that interaction between an application and a webbsite differs much because of technical conditions such as screen size or limits as a result of rigid interface guidlines. Graphical elements are influenced by the publishers own guidlines for graphical user interface. The company’s own webbmanual is used as a template when developing the applications and keeping the identity intact. This applies to all the interviewed developers. The use of designpatterns occurs in most cases. The interviewed companys agree that design patterns should be applied to the process but some of the informants only apply them in interaction design and not in graphic design.