A method is proposed for the long-term strength predictions for chromium-nickel austenitic steels based on short-term experimental tests. The experimental data consists of a series of creep diagrams for various applied stresses and temperatures, as well as of the tentative values of the failure time. The long-term strength and creep experiments are illustrated by the results for the steel 08X16H11M3. The metallographical studies of the samples tested in long-term strength and creep experiments are carried out. The microstructure of the deformed sample metal and the failure nature are analysed for various temperature regimes.