The use of Armour Thyroid (desiccated thyroid) in the treatment of hypothyroidism has generated debate among endocrinologists although there is evidence that a significant percentage of patients prefer this medication to T4-only replacement strategies. In this retrospective analysis we investigate the preference for replacement therapy of patients with persistent subjective symptoms of hypothyroidism on T4-only treatment who subsequently switched to Armour Thyroid (AT). Methods: 450 consecutive patients being treated for hypothyroidism were screened. Of these, 154 had been switched from either generic or brand T4 replacement to AT for treatment of persistent symptoms of hypothyroidism. Patients undergoing treatment for thyroid cancer or on suppression therapy for nodular thyroid disease were excluded. Patients were instructed to have their blood sampled for thyroid function testing in the morning after taking their medication. After a minimum of 4 weeks on medication patients were asked to compare AT treatment versus T4-only treatment using a 5 point satisfaction rating scale. Results are reported as mean ± SD. Results: On a 5 point Satisfaction Rating Scale with “5” indicative of the highest level of satisfaction, 117 (78.0%) patients gave a score of greater than “3” in preference for AT. Three patients treated with AT and one treated with LT4 reported adverse events, all minor. TSH was 1.30 ± 1.9 mIU/L and T3 1.81 ± 0.78 pmol/L on L-T4 monotherapy while TSH was 1.27 ± 2.2 mIU/L and T3 2.31 ± 1.33 pmol/L on AT (NS for TSH and p<0.003 for T3 ). T4 to T3 ratio on L-T4 monotherapy was 8.45 ± 3.7 while it was 4.70 ± 2.0 (p<0.001) on AT. There was no significant change in weight after switching to AT. Conclusion: AT treatment was preferred over LT4 replacement therapy by 78% of patients with hypothyroidism in the sub-group with persistent subjective complaints while on T4-only therapy. No serious adverse events were noted while on AT treatment including 30 subjects aged 65 yrs or older. AT could be a reasonable alternative choice for treating this sub-group of patients with hypothyroidism.