The potential of oyster mushrooms to attack and kill sugar beet cyst nematode (Heterodera schachtii) was studied. The ability of Pleurotus ostreatus, P. sajor-caju, P. florida, P. flabellatus, P. ostreatus (sporeless) , P. eryngi and Hypsizygus ulmarius to prey on the cyst nematode was confirmed. Nematodes were inoculated on water agar plates on which a single sparse fungal colony of one of the above mentioned fungi was grown. Nematodes were quickly immobilized after inoculation the plates with each Pleurotus species, with mortality of about 96%, 72%, 55%, 52%, 20%, 23% and 62%, respectively. Nematicidal activities of culture filtrates of Pleurotusspecies and H. ulmarius against H. schachtii were also studied in vitro. Extracts of P. ostreatus could paralyse 90% of nematodes whereas P. eryngii could paralyse only 50% of nematodes. The efficacy of old mushroom compost from cultures of P. ostreatus and P. sajor-cajuin controlling cysts on sugar beet (Beta vulgaris ICI) were studied under greenhouse conditions. The results showed that 100 and 200 grams of mushroom compost per 3 kilogram/pot could significantly control cysts, reducing more than 85% cysts in soil. Presence of cysts on the roots and larvae inside roots were compared with the control treatment.