The present research was conducted to investigate benthos communities and their population structure in River Haji Abad located in the west of Hormozgan province during October 2012 to September 2013. In total, three study stations were determined based on the region’s topography and taking triplicate samples at each station, its macrobenthos fauna was sampled monthly using 500 micron Surber sampler. Using formalin 4%, samples were fixed and isolated, identified and counted in the laboratory of Azad University, Bandar Abbas branch. In total, 5 classes, 9 orders and 24 families were identified, where aquatic insects’ larvae had the highest diversity and abundance among the samples. Individuals belonging to the two orders of Diptera and Ephemeroptera were dominant in all the three stations. The maximum abundance of all organisms in this period was 4195 per sq.m in station 3 and the minimum was 2935 per sq.m in station 1. The data related to macrobenthos were summarized as community structure metrics including EPT index (Ephemeroptera, Plecoptera, Trichoptera) and the ratio of the abundance of EPT to Chironomidae family. In addition, Shannon Wiener diversity index and Bauer bio indicator were also investigated and calculated in the stations. Station 2 has had the highest diversity of species from Shannon Wiener diversity index viewpoint. From Bauer index viewpoint, station 2 has also had the least pollution during the year in comparison with the other two stations.
