Introduction. Resistance to thyroid hormone is a rare syndrome, where although the level of thyroid hormone is elevated, the level of thyroid stimulating hormone is not suppressed. The patient in our case report is, to the best of our knowledge, the first with this syndrome identified in Oman. Case presentation. In one Omani family, a 15-year-old girl of Arabian origin was pre-diagnosed with resistance to thyroid hormone. Blood sample was collected and deoxyribonucleic acid was isolated for molecular genetic testing. The results revealed a rare mutation A268G in the gene for thyroid hormone receptor beta. We believe that this mutation is the cause of the pathology in our patient. Conclusion: We report the presence of a rare mutation in the thyroid hormone receptor beta gene for the first time in the Omani population. Due to the rates of consanguinity being high among the Omani population, we are aiming to screen our patient's family members and provide genetic counseling.