We examined the role of comorbidity in models that use the illness perceptions of patients with somatoform disorders to explain their outcomes. A total of 138 primary care patients with somatoform disorders completed the Patient Health Questionnaire and Brief Illness Perception Questionnaire and rated their general health status. Medical comorbidity was rated by the general practitioner. Patients’ illness perceptions were consistently related to their outcomes independent of medical and psychological comorbidity in our models. At the same time, inclusion of comorbidity enhanced our models, revealing differences in the relevance of the specific comorbidity depending on the outcome measure.