Objectives To analyse the prevalence of hypothyroidism in rheumatoid arthritis (RA) patients and to elucidate its correlation with disease activity. Methods A total of 52 RA patients were enrolled in this study. All patients were assessed fully clinically and underwent routine laboratory investigation including thyroid function testing. Results Hypothyroidism (defined as having a TSH level >4.20IU/mL) was observed in 20/52 (38.4%). Erythrocyte sedimentation rates (ESR) were found significantly elevated in patients with hypothyroidism compared to those without (36.324.2 vs. 24.6 +/- 9.0mm/h). Disease activity parameters such as DAS-28-ESR, tender joint count; VAS scores were also significantly higher in the former. A significant correlation with serum TSH levels was observed with ESR and DAS-28-ESR. Conclusion Thyroid function test should be included in clinical evaluation of RA patients.