objective: to describe and discuss evidence-based articles on the neurobiology of obsessive-compulsive disorder and tourette syndrome. sources of data: a review of the most relevant papers on the phenomenology, neuroanatomy, neuroimaging, genetic and immunological aspects of these two disorders was performed. summary of the findings: ritualistic behaviors and repetitive thoughts have been extensively studied in the last years. the definitions of obsessive-compulsive disorder and tourette syndrome emphasize the existence of a continuum of symptoms, with high prevalence in the general population. neurobiological findings have implicated genetic and immunological factors in the etiology of these two disorders. conclusions: advances in neuroscience triggered genetic and immunological research studies, allowing new perspectives on the treatment of obsessive-compulsive disorder and tourette syndrome patients.