The article deals with the growth of nuclear medicine in India. Radiopharmaceuticals both in elemental form and radiolabelled compounds became commercially available in India in 1961. Objectives and educational efforts of the Radiation Medicine Centre setup in Bombay are mentioned. In vivo tests of nuclear medicine such as imaging procedures, dynamic studies, dilution studies, thyroid function studies, renal function studies, linear function studies, blood flow, and absorption studies are reported. Techniques of radioimmunoassay are also mentioned.