Neutron activation analysis is a sensitive and quantitative tool used in determining the interior structure and composition of art objects. The procedure involves bombardment of a sample with nuclear particles. This converts some of the atoms in the sample into radioisotopes. The induced radiation is measured to provide information that will determine the presence of some chemical elements. The sampling process is nondestructive. The radiation dose is low; the integrity of the object is preserved. Sampling is discussed. Several examples of investigations are presented: trace elements in Devon pottery and Sassanian silver. The problem of variations in metal composition in the interior and surface levels is mentioned. The autoradiography of paintings is discussed, as is the regeneration of early, faded, photographs by the Same technique. The text explains the identification of pigments in a painting by NAA.