Abstract: This study evaluated the quality of the effluent water of El-Tall El-Keber wastewater treatment plant, Egypt by using aquatic insect Chironomus calipterus larvae as bioindicator. Larvae, water and sludge samples were collected from input and output lagoons to determine the levels of heavy metals (Mn, Fe, Zn and Pb) throughout the process of treatment. The results of the heavy metals analysis of samples collected at the input lagoon indicated that Fe was the most abundant metal at different seasons, while Pb exhibited the lowest abundance in all sludge samples collected from either input and output lagoons. The levels of Fe and Zn were reduced in output lagoon by 8.4-64.5% and 20.7-37.4% at different seasons, respectively. Accumulation of heavy metals in the larval tissues differed by different seasons for the same lagoon and can be arranged descending as following: Fe>Zn>Mn>Pb. The results indicated that larvae of C. calipterus Kieffer had high capabilities to accumulate certain heavy metals and could be used as heavy metal bioindicator. The potential use of these larvae in wastewater treatment is worth to do further exploration.