From rebuted hypothesis to Nobel prize. The invention of radioimmunoassay (RIA) techniques by R. Yalow and S. Berson opened new horizons to many branches of life sciences. Their first paper describing the immunoassay of plasma insulin in human subjects, has been published in Nature just 50 years ago. The authors did not patent their invention, giving thus everybody the opportunity to use it freely. Spectrum of RIA applications extended promptly into many areas - e. g. analysis of hormones, drugs, vitamins, serum proteins and diagnostic markers, viruses and bacteria.