INTRODUCTION: Few cases of obsessive-compulsive disorder (OCD) symptoms preceding the clinical onset of Huntington Disease (HD) or during later stages of the disease have been reported in the literature, but the nature of this association and its neurobiological mechanisms have not been well-investigated. OBJECTIVES: To review the scientific literature regarding OCD symptoms in patients with HD and describe a case study from our clinic. METHODS: Extensive literature searches were performed to identify reports of patients with concurrent HD and OCD symptoms. RESULTS: Recent studies and the current case report suggest that OCD symptoms may predate or coincide with motor, affective or behavioral symptoms in patients with HD. The development of OCD and HD symptoms may involve structural and functional changes affecting the orbital and medial prefrontal cortex, ventromedial caudate nucleus, and pallidal sites. CONCLUSIONS: Some patients with HD develop symptoms associated with OCD. Progressive and differential neuropathological changes in the ventromedial caudate nucleus and related neural circuits may underlie this association. No specific treatment strategy has been developed to treat these patients; however some medications attenuate associated symptoms. Further testing is needed to determine the neurobiological mechanisms of these disorders.