Résumé : Human blood cells harvested in vitro were irradiated at the 55th hour with 35MeV electrons. Five samples of cultures received 200 r at different dose rates of respectively 10, 50, 100, 250 and 450 r/min; 5 other samples were irradiated in the same conditions with 400 r. One hit chromosomial aberrations were not dose rate dependent whereas 2 hit aberrations were related to dose rate. © 1967.