METHODS: Seventy-one patients diagnosed with primary hypothyroidism were randomly allocated into two study groups: the first group received usual dose of levothyroxine and the second group received combination of levothyroxine and liothyronine for at least 4 months. The main outcomes were psychosocial problems (Goldberg's General Health Questionnaire, GHQ-28), bodyweight, heart rate, blood pressure, and serum lipid levels. RESULTS: In both groups serum thyroid-stimulating hormone levels remained unchanged compared with baseline. Psychosocial scores, body weight, heart rate, blood pressure, and lipid profile in the two groups remained constant. The only exception was a small but significant reduction in anxiety/insomnia in combined treatment group as compared with monotherapy.