CASE REPORT: A 35-year-old lady, post-radioactive iodine therapy for Graves' disease remained euthyroid for a year on oral LT4. Two years later, she was clinically and biochemically hypothyroid despite claiming LT4 compliance. As all laboratory investigations were within the reference range, pseudomalabsorption was suspected and a LT4 absorption test was done. During the test, her free thyroxine increased significantly at 4 hours, reaching a peak of more than 50% from baseline while TSH decreased appropriately from 0 minute to 360 minutes. This was followed by normalisation of TSH with LT4 treatment under direct observation.