Mushrooms are one of the newest resources in the human food basket. Agaricus bisporus (J.E. Lange) Imbach, 1946 is the most cultivated fungus for the purpose worldwide, which was grown in small and huge amounts and used cooked or uncooked. Growing beds of the mushroom because of providing good conditions of humidity, air condition, temperature, and food resources are very optimum and suitable places for the growth and living of different plant parasitic organs as well as diverse pests. Nematodes, like other microfauna members, prefer to live in such places. In order to study the nematode biodiversity in mushroom producing composts, during 2023 several samplings were carried out in commercial and personal mushroom growing beds. Nematode extraction, killing, fixation, preparing slides, and identification were done using ordinary methods in nematology and using references. In this text as a second part, three species, namely Cephaloboides curviacaudatus, Rhabditiella axei, and Mesorhabditis sp., are reported and described. Genus Cephaloboides is here introduced as a new member of the nematode fauna in Iran.
