The pharmacologic treatment of the delusional disorder is a neglected topic in psychiatric literature. Pimozide is often quoted as the treatment of choice. Following a clinical case the authors critically appraise the literature on the treatment of delusional disorder of the paranoid type with pimozide. The literature consists of case studies and studies with serious methodological shortcomings. In addition the efficacy of neuroleptics is not demonstrated for this kind of disorder. Further controlled research is therefore required.