Research on obsessive-compulsive disorder (OCD) has advanced substantially since the DSM-IV was published in 1994. It is time to reexamine the nosology of this disorder, reviewing conflicting views regarding the classification as well as subtypes and specifiers of OCD. Although there is ongoing debate, OCD experts have suggested that OCD be retained in the section related to anxiety disorders and also that along with OCD, this section include obsessive-compulsive spectrum disorders (OCSD), a group of disorders closely related to OCD. A combined 'anxiety and obsessive-compulsive spectrum chapter' has also been proposed to include OCSDs. A growing body of scientific data has provided empirical support for the inclusion of a 'tic-related' subtype of OCD in the DSM-V. However, it remains controversial as to whether to introduce OCD symptom dimensions as specifiers as well as items in the diagnostic criteria. With regard to compulsive hoarding, there has been sufficient evidence to recommend that it be classified in the DSM-V as a separate disorder. Much work remains in order to ensure that the DSM-V is as evidence based as possible. It is necessary to strive toward integrating the biological and psychological data related to OCD and OCSD based on their endophenotypic features