Background: "The greatest burden of oral diseases is on the disadvantaged and socially marginalized populations"The World Oral Health Report(WOHR) . Such diseases also undermine self-image and self-esteem, discourage normal social interaction and lead to chronic stress, depression as well as incur great financial costs. Aim: Relationship of psychiatric disorders with deleterious habits, oral mucosa conditions, TMJ assessment. Methods: A cross sectional study with simple random sampling of 700 psychiatric patients aged between 35-74 years attending the psychiatric out patient department of two government hospitals ie. Patna Medical College and Hospital (PMCH) & Nalanda Medical College and Hospital (NMCH). Results: Among psychiatric patients, majority had not been previously admitted to the hospital, 90 percent were seen to have history of medication and majority had dry mouth problem. Majority had clicking in TMJoint among which majority had shizophrenia. It is actually surprising that patients had no tenderness in TMJoint even though bruxism habit was quite prominent in the subjects. Among them majority were on medication out of which, majority had oral mucosa condition. In mucosal conditions majority had aphthous ulcers which is also related to the presence of 71% of subjects with xerostomia. Associations were statistically significant(p<0.001). Conclusion: An oral health care system must have three concurrent approaches to care: treatment of oral diseases, oral diseases prevention, and oral health promotions In order to gain a deeper understanding of the research area, further investigations of oral health in psychiatric populations both hospitalized and in outpatient care is needed.