Background In Europe, hospital training is integrated in the postgraduate curriculum of General Practitioners (GPs) according to the European Directives. However, little is known about the specific learning objectives of GP trainees during this training.Objectives This exploratory study investigated GP trainees’ expected learning objectives for their hospital training and the factors influencing the learning process.Methods Semi-structured interviews were conducted in three focus groups consisting of first-year GP trainees before their hospital training. Data were coded thematically and analysed in NVivo.Results A total of 22 Belgian GP trainees (55% females, average age of 26.2 years) were interviewed. Three major themes emerged: learning objectives, factors influencing learning and organisational aspects. GP trainees mainly wanted to improve their knowledge of common conditions by conducting consultations and follow certain patients’ hospitalisation trajectory. Emergency medicine or internal medicine was the preferred specialty. Other GP trainees wanted to learn more about some specific conditions. Conversely, an overloaded work schedule was dreaded to hinder effective learning. Regular meetings and supervision from their hospital trainer were deemed crucial to strengthen GP trainees’ learning trajectory.Conclusion GP trainees wanted to learn more about both common conditions and some specific conditions. Their previous year in a GP setting strengthened their confidence and facilitated purposeful learning. Relieving GP trainees from administrative tasks when working as supplementary doctors could strike a better balance between the continuity of the clinical department and their personal learning objectives.