INTRODUCTION: The system of countermeasures for the adverse effects of microgravity developed in the USSR supported the successful implementation of long-duration spaceflight (LDS) programs on the Salyut and Mir orbital stations and was subsequently adapted for flights on the International Space Station (ISS). From 2000 through 2010, crews completed 26 ISS flight increments ranging in duration from 140 to 216 d, with the participation of 27 Russian cosmonauts. These flights have made it possible to more precisely determine a crewmember’s level of conditioning, better assess the advantages and disadvantages of training processes, and determine prospects for future developments.Koslovskaya IB, Yarmanova EN, Yegorov AD, Stepantsov VI, Fomina EV, Tomilovaskaya ES. Russian countermeasure systems for adverse effects of microgravity on long-duration ISS flights. Aerosp Med Hum Perform. 2015; 86(12, Suppl.):A24–A31.