Introduction: Mental illness has often been associated with thyroid dysfunctions and if left untreated it can further aggravate the severity of underlying disease. Objective: The study was planned to assess psychiatric co-morbidity in patients with thyroid disorders using GMHAT questionnaire. Methods:  The study was commenced after ethical clearance from IEC.  All the patients >18 years of age, attending the endocrinology OPD were screened for inclusion in the study.  Based on the diagnosis established by the Endocrinologist, the study subjects were divided into hyperthyroid (n= 40) and hypothyroid (n=70) groups.  Age and sex matched controls (n=50) were also included. All the selected participants underwent psychiatric evaluation through structured interview using the Global Mental Health Assessment Tool, Primary Care Version (GMHAT/PC) questionnaire.  The data were compiled and appropriate statistical tests were applied. Results:  As per the structured GMHAT interview, out of 70 hypothyroid patients, 31 were found to have psychiatric disorder.  In the hyperthyroid and control groups, 2 participants each were diagnosed with psychiatric disorders. Psychiatric co-morbidities observed in the participants ranged from anxiety, depression, mania to obsessive compulsive disorder (OCD).  Significant association was observed within the three groups; X2 (2, 161)=37, P<0.0001). Result implies that patients with hypothyroidism are 15 times more likely to have mental illness as compared to hyperthyroid (OR-15.1; 95% CI – 3.4-67.5) and 19 times more likely to have mental illness than normal individuals (OR-19.1; 95% CI – 4.3 – 84.7).   These symptoms were observed in hypothyroid as early as 2 months of the disease onset. Conclusion:  Patients with hypothyroidism have high psychiatric comorbidity with an early onset.  Medical experts should be aware of this fact and can be trained to identify mental illness using a standard and validated easy tool GMHAT/PC. It is recommended to safeguard the mental health of these patients and implement efficient holistic approaches at the earliest to improve their overall outcome and quality of life.