The participating patients in clinical trials are sometimes asked to fill in a patient diary to keep track of their health, often using modern IT infrastructure. This is referred to as electronic patient reported outcome, e-PRO. Since year 2000 Nordforce has developed and operated a number of different e-PRO systems, based on various technologies such as Smartphones, SMS and Web. Our solutions have been used in in clinical trials in large parts of the world, and by some of the top 10 largest pharmaceutical companies in the world.The challenges in all these projects have been to obtain optimal usability and also to ensure that the patient data always is retrieved even when the communication network fails from time to time. Of paramount importance is the conformance with the rigorous Good Clinical Practice standard.