Abstract: Recently, American Thyroid Association and American Association of Clinical Endocrinologists published Clinical Huideline for Hypothyroidism. The authors took an evidence-based medicine approach, and created 52 recommendations on 15 issues. The guideline emphasized that serum thyrotropin is the single best screening test for primary thyroid dysfunction for the vast majority of outpatient clinical situations. The standard treatment for hypothyroidism is replacement with L-thyroxine. The decision to treat subclinical hypothyroidism when the serum thyrotropin is less than 10 mIU/L should be tailored to the individual patient.