Obsessive Compulsive Disorder is a psychiatric disorder, which was studied on mice to examine its biological basis and identify a possible treatment. Current treatments for OCD include pharmacotherapy with serotonin reuptake inhibitors (SRIs), which include the selective SRIs and the tricyclic antidepressant clomipramine. The purpose of the treatment is mainly to elevate extracellular levels of 5-HT, which has a strong correlation with reduction of OCD symptoms. SRI treatments provide the only effective pharmacological monotherapy for OCD, however, 40–60% of OCD patients do not respond to SRI treatment, and those who do often exhibit a partial response (Hollander and Pallanti, 2002). This might be due to the fact that the specific receptors that facilitate the increase of 5-HT levels were not targeted, and we know very little about them. The 5- HT2C receptor is a possibility due to evidence supporting their role in some patients. In this study, 5-HT2C KO mice with disrupted receptors have been extensively characterized and compared to WT mice. This assessment may provide a novel animal model of OCD, which is the initial step of establishing models for studying mechanistic aspects of OCD. Chewing of non-nutritive clay, chewing patterns on plastic-mesh screens, and the frequency of head dipping were measured. In addition to exhibiting hyperphagia, knockout mice showed increased chewing of inedible objects. The chewing patterns of plastic screens in knockout mice were found to be more “neat” and organized as opposed to those of WT mice. KO mice were found to chew more clay than WT mice as well. Finally, 5-HT2C KO mice were reported to exhibit more head-dipping behavior than WT mice, which was suggested to reflect a form of nonoral compulsive behavior. Overall, the results of this study bring about a mix of results may or may not validate aspects of OCD. The increases in behaviors defined as “compulsive” can be argued to have face validity for OCD. Head-dipping behavior can be considered a measure of exploration/anxiety rather than a compulsive behavior. Regardless, the results were found to be statistically insignificant.