Environmental stress caused by pollution is often assessed by diversity of macro-invertebrate species in specific aquatic habitat. To find out seasonal fluctuations in various macro-invertebrates communities and different water quality parameters of River Zhob, a research trial was conducted on River Zhob, Balochistan. Samples of macro-invertebrates and water were taken from four different stations of River Zhob. A total 18 taxa of various macro-invertebrates were identified from the area. Phylum Arthropoda constitute 94.8% of the total population followed by Mollusca (3.6%) and Annelida (1.4%). A large number of arthropods were belonged to order Diptera (1148), while the order Trichoptera was stood second with respect to macro-invertebrate´s number (441). The maximum numbers of macro-invertebrates were observed in the month of January. All physico-chemical parameters of River Zhob such as air temperature, water temp, pH, dissolved oxygen (DO) and total dissolved solids (TDS) were within the range, suitable for the healthy growth of macro-invertebrates. Diversified populations of various macro-invertebrates confirm good ecological condition of environment and water in the studied site especially ample concentration of DO in River. The documented data on macro-invertebrates in studied site will provide a baseline for future research.