A survey of Globodera rostochiensis infested field in Velingrad region (South-West Bulgaria) revealed the spread of a black egg disease in the old cysts. The fungus mycelium infected the embryos within the egg shell. The highest egg parasitization by fungi was observed during June (22.2%). The fungus destroyed the new progeny in September. Four species of nematophagous fungi were isolated from cysts and eggs: Botryotrichum piluliferum Sacc.