Iran is a vast country located in the Middle East. It has different climates which make the country rich in terms of biodiversity. Nematological research inside the country has a high importance. This book meets all records on free living bacterivorous nematodes occuring in terrestrial and aquatic ecosystems in Iran; these belong to the order Rhabditida. A total of 88 species belonging to 39 genera and 15 families are included. Description, measurements and illustrations are provided for all of them.