Patients with a delusional infestation (DI) have an overwhelming conviction that they are being infested with (non) pathogens without any medical proof. The patients need a systematic psychiatric and dermatological evaluation to assess any possible underlying cause that could be treated. Because they avoid psychiatrists, a close collaboration of dermatologists and psychiatrists, who examine the patient together, seems to be a promising solution. It helps to start a trustful doctor-patient relationship and motivates the patient for psychiatric treatment. We here review diagnostic criteria, classification of symptoms, pathophysiology and treatment options of DI. Antipsychotic medication is the treatment of choice when any other underlying cause or disorder is excluded. Further research is needed to assess the pathophysiology, and other treatment options for patients with DI.