Nowadays, the population is ageing, which together with current lifestyles is contributing to a major prevalence of chronic diseases. In this scenario it is important to provide good healthcare services without increasing associated costs. A prominent way to tackle this challenge is through the application of personal health systems (PHSs), which provide monitoring technologies to patients in order to help them with the self-management of chronic diseases. In this context, agents can simplify the modelling of PHSs as they are autonomous software entities that pursue a set of goals in an intelligent way, by applying artificial intelligence reasoning techniques. In the MAGPIE project we propose the use of multiagent systems (MAS) in PHSs as a solution for monitoring patients affected by chronic diseases.