For the general practitioner scintigraphic investigation of the skeleton and the lung and the isotope techniques for evaluation of diseases of the thyroid are important. Scintigraphy of the skeleton and the lung, the latter consisting of ventilation and perfusion tests, are briefly described. Examples are used to outline the most important indications for these studies. Investigations of the thyroid comprises basic procedures such as chemical tests, sonography, scintigraphy, eventually complemented by fine-needle aspiration, as well as treatments with radioactive iodine isotopes. Finally, the recently introduced densitometry of bones is briefly discussed.