Health professionals increasingly face patients with complex health problems and this pressurizes them to cooperate. The authors have analyzed how the complexity of health care problems relates to two types of cooperation: consultation and multidisciplinary teamwork (MTW). Moreover, they have analyzed the impact of these two types of cooperation on perceived professional autonomy. Two teams were studied, one team dealing with geriatric patients and another treating oncology patients. The authors conducted semi-structured interviews, studied written documents, held informal discussions and observed (...) the teams at work. Consultation was most likely to take place when a patient had multiple problems. However, if these problems were interrelated, i.e. the solution for one problem interfered with solving another, then MTW was favored. The same was true when the available information was equivocal such that there were conflicting interpretations of a problem. How the professionals perceived the relationship between complexity and the need to cooperate depended on their expertise, their occupational background, and their work orientation. Consultation did not affect the professional autonomy of the health care professionals. MTW however did decrease the perceived level of professional autonomy. The extent to which this occurred seemed to depend on the quality of the interpersonal relations within the team. The findings can help in selecting the most appropriate and efficient type of cooperation based on the complexity of a patient’s problems. They can also help team leaders to stimulate reflection and feedback processes, and medical trainers to develop competencies among students related to such teamwork behaviors. (shrink)