Thyroxine is the standard replacement therapy for patients with clinical hypothyroidism. However, there has been recent interest in examining the potential advantages of combined thyroxine and triiodothyronine treatment for the treatment of hypothyroidism. The authors review the nine studies to-date and conclude that the variability and limitations in study design make definitive and clinically useful recommendations difficult. They therefore conducted a metaanalysis of the nine controlled studies examining the impact of combined thyroxine-plus-triiodothyronine versus thyroxine alone, with measures of psychiatric symptoms as the primary outcome. Their analysis reveals no significant difference in treatment effect on psychiatric symptoms in the nine controlled studies to date.