Thyroid scintigraphy is required during the initial assessment of an isolated thyroid nodule. This is the only means of diagnosing a hot, cold or self-fixing nodule. The isotope used can be either radioactive iodine or pertechnetate Tc04. For a number of authors, the best images are obtained with iodine; Tc04 is less expensive and easily available. Only scintigraphy can highlight the true problems. Is a cold nodule benign or malignant? A fine-needle aspiration biopsy is performed, then controlling the size if surgery is unnecessary. Is it a hot toxic nodule, or is it likely to become toxic? The ultrasensitive TSH is monitored. The malignant hot nodule problem remains theoretical. Well-documented observations are still rare. The role of scintigraphy in the initial sequence of an isolated nodule investigation is discussed. The main limit of scintigraphy, which is its poor resolution, may offer the advantage of reducing ultrasound microsemiology abuse.