This study was undertaken to evaluate the factors affecting the abundance of rhabditid nematodes in the farms of Khorramabad city of Lorestan province, Iran. Nematode communities as well as rhabditids population reacted to the soil pH and the type of crops cultivated at each sample point. Crop type affected nematode populations mainly due to their root systems. Also, the abundance of r habditid nematodes decreased at lower pH of the soil. Since some of the nematodes are entomopathogenic hence, results of the present study are important in terms of biological control of soil pests which leads to preservation of agro-ecosystem through less use of chemical pesticides and achievement of a sustainable agriculture.