Common physical symptoms such as abdominal pain, headache, back pain and dizziness play a major role for the health care system. Existing models for the development and maintenance of these symptoms emphasize a vicious circle with cognitive-perceptual, behavioral, and psychobiological components. In this manuscript, we present examples of psychobiological factors that might contribute to somatoform disorders. We emphasize that somatoform symptoms are not strictly mental events, but are associated with a diversity of biological processes. The possible role of the endocrine and immune system, amino acids and neurotransmitters, but also physiological activation and cerebral activity is exemplified. These approaches are categorized using a model of perception and filtering of bodily signals. Studies are needed that combine the investigation of different biological systems with assessments of psychological variables in longitudinal trials, but also experimental investigations in humans examining the interaction of behavior changes, biological variations, and body perception are still rare.