In general practice, we see complexity in the patient ('case complexity'), in the treatment ('care complexity'), and, to an important degree, in the context in which patient characteristics and environmental factors together lead to disease ('complexity thinking'). This context makes linear medical thinking, i.e. in which a symptom of a disease has one direct biological cause, problematic and the outcomes of interventions based on this thinking are uncertain. Complex patients make much greater demands on a practice than average. Complex interventions occur mainly in the context of coordination of collaboration with other professionals. Complex systems thinking has taken root in general practice, certainly in the scientific field. General practice is often complex, and the only good way to practice is to provide personal care with a focus on the context in which the health problems occur.