BACKGROUND Although lithium is known to cause thyroid dysfunction and increased thyroid gland volume, clinical examination and biochemical assessment are fundamental to thyroid workup of patients on lithium treatment. We aimed to determine thyroid gland volume and the Thyroid hormone levels of patients who have been receiving lithium treatment for affective disorders in comparison to voluntary healthy controls. METHODS This was a cross-sectional, hospital-based observational study which was performed in 43 patients on long-term lithium treatment for bipolar disorder, major depressive and schizoaffective disorders. Patients with documented continuous and adequate serum lithium levels for more than or equal to 6 months recruited consecutively underwent the ultrasonographic examination of the thyroid gland. Ultrasonographic examinations were also done in all gender- and age-matched healthy controls. All cases and controls underwent biochemical thyroid function tests. RESULTS There were no statistically significant differences in gender (P = 0.198; Chi-square = 1.654) of cases and controls. Most of the cases were married, maximum number of them unemployed and belonged to the lower socioeconomic status. Total thyroid volume was significantly greater in the lithium-treated group than the controls (9.40 ± 1.41 vs. 4.79 ± 0.45). Clinical inspection and palpation only detected goiter in six (n = 6, 13.95%) of patients on lithium and none among controls. The mean triiodothyronine, mean thyroxine, and mean scores for thyroid-stimulating hormone were significantly increased in patients receiving lithium therapy as compared to controls. CONCLUSIONS It would seem wise from a clinical point of view to include ultrasonographic examination of the thyroid gland as part of the standard thyroid workup before initiating lithium treatment.