This paper reports on multiple employment among Portuguese health sector workers, using data obtained from six studies. The methodological aspects of these studies are briefly summarized. The prevalence among the study populations varies between 5 and 80%. When the first job is in the public sector, the site of additional employment is most frequently another public sector facility. Multiple employment is more prevalent among hospital workers; it is more frequent among those working shifts or part-time, and least frequent among professionals with a contract that requires exclusivity. Physicians with multiple jobs were more likely to have low expectations of getting promoted and to assess the rewards for their work as inadequate. For most nurses the salary increment resulting from multiple employment was less than their public sector salary. For both groups, improving income levels and higher job satisfaction were important reasons to seek additional employment. For physicians working in public services, access to more professional autonomy was an important reason for seeking additional employment in the private sector.