In 1987, the revision of the DSM-III reintroduced the concept of paranoia under the name of delusional disorder. Most of the actual evidence about the pharmacological treatment of this disorder is derived from case series and case reports. Antipsychotics have been used for the treatment of delusional disorder since 1970s, with pimozide as a first line drug. The introduction of second generation antipsychotics changed the treatment of the disorder. In spite of the available information, delusional disorder remains to this day a controversial and complex disorder.