Clinical research is largely focused on depressive comorbidity in obsessional compulsive disorder (OCD). However some recent publications have suggested that bipolar comorbidity occurs in authentic OCD and its presence has a differential impact on the clinical picture and course of OCD.Recent data from the collaborative survey conducted with AFTOC (French Association of patients suffering from OCD) have revealed a high rate of bipolar comorbidity in OCD: 30% for hypomania and 50% for cyclothymia.The present paper presents further comparative analyses between OCD with (n = 302) versus without cyclothymia (n = 272). The sub-group "Cyclothymic OCD" is characterized by a different clinical picture (higher frequency of aggressive, impulsive, religious and sexual obsessions, and compulsions of control, hoarding, repetition), episodic course, higher rate of major depressive episodes (with more intensity and recurrence) associated with higher rates of suicide attempts and psychiatric admissions, and less favorable response to anti-OCD treatments.These data suggested that cyclothymic OCD could represent a specific distinct variant form of OCD. More vigilance is needed toward this entity which is largely under-recognized in clinical practice.