Even though burnout is one of the most widely discussed mental health problems in today’s society, it is still disputed and not officially recognized as a mental disorder in most countries. In the tradition of the social study of science, the objective of this article is to analyze how burnout has been investigated in the health sciences in the past four decades, and how this has influenced the ways burnout is understood today. We conducted an extensive quantitative and qualitative literature analysis on all publications on burnout listed in PubMed until 2011. We show that the number of publications on burnout increased considerably over the past 40 years, and identified six categories into which each study can be grouped. The studies are not equally distributed across the categories: Most focus on causes and associated factors. Only a very small number of articles deal with psychological and somatic symptoms of burnout and attempt to develop diagnostic criteria. We argue that just this distribution is the reason why burnout research reproduces the vagueness and ambiguity of the concept that it aims to clarify, and discuss our results in the light of the concept of medicalization.