Two AML patients treated with recombinant interleukin-2 infusion without LAK cells developed thyroid complications within 2 months following the treatment. One patient was clinically and biochemically hypothyroid but was negative for thyroid autoantibodies while the other patient developed thyroid microsomal autoantibody but remained euthyroid. These 2 cases represent the two ends of the spectrum of thyroid complications following interleukin-2 therapy. Such complications are not uncommon but are poorly documented. We suggest that patients receiving cytokine therapy should be followed up closely for any autoimmune complications.