Some species of higher fungi growing at localities with increased contamnation by fission products from radioactive fallout /about 10–20 kBq137Cs m–2 and more/ contain up to 200 kBq of radiocesium-137Cs and134Cs, per kilogram d. m. Simple isolation of the rationcesium preparation of fruittbodies of suchn mushroom accumlators of radiocesium is described.