This paper was presented as part of the student paper contest associatedwith the European Petroleum Conference. Abstract This paper gives an overview over the different aspects of transientpressure behaviour in fractured reservoirs. Basically fractured reservoirs can be divided into two different groups. Thefirst consists of reservoirs of single porosity which have been fracturedartificially, the second group consists of reservoirs which contain a networkof natural fractures and which have been additionally fractured artificially(double porosity fractured reservoir). Further it is possible to make adifference based on the radial dimensions and the boundary conditions of areservoir. Therefore the systems of infinite and finite reservoirs will also bediscussed. These four cases will be presented separately. The different flow regimeswill be discussed and also the parameters which influence the pressurebehaviour. Further the interpretation of the pressure tests will be discussed by usingthe type curves which correspond with the results of the flow regimesdescription. Finally a short brief of the simulation of the two main different fracturedreservoirs on a numerical reservoir simulator will be given. Introduction To enhance the productivity of wells which were damaged or were completed intight formations, hydraulic fracturing (called "HF" in the followingtext) is a common and often used technique. Hydraulic fracturing as well asacidicing have been used with great success in many reservoirs with low naturalpermeability. It was realised very early that a HF influences the flowbehaviour of a well extremely, so that common pressure test analyses techniquesmay cause errors. Thus the transient flow behaviour of fracturedreservoirs became an important topic. The different analyses of the pressure tests do not only describe the statusquo of the flow behaviour after the treatment but describe also the form of theHF. The interpretation of the tests is very important for the productionstrategy and even for the design of a new HF.