The present study was conducted to determine the concentrations of heavy metals Zn, Fe, Cu, Mg and Mn in muscle tissue of the two weight classes of green tiger shrimp, Penaeus semisulcatus including the shrimps with a mean weight of 11.70-25.50 g (n=75) (first class) and 50-101.40 g (n=19) (second class). Shrimp samples (n=94) were collected from coastal waters of Bahrekan, Khuzestan province, Iran during October, 2015. A flame atomic absorption spectrophotometer was used to measure the heavy metal concentrations in muscle tissue of shrimps. Based on obtained results, the average concentrations of 7.75±0.12, 1.29±0.19, 3.02±0.04, 0.10±0.05 and 0.57±0.05 mg/kg.wet.weight were found respectively for Zn, Fe, Cu, Mg and Mn in shrimps of first weight class. For shrimps of second weight class, the average concentrations of Zn, Fe, Cu, Mg and Mn were 7.68±0.04, 1.17±0.03, 2.96±0.06, 0.11±0.02 and 0.52±0.06 mg/kg.wet.weight respectively. There were no significant differences in concentrations of measured heavy metals between two weight classes of green tiger shrimps. In conclusion, the concentration of all measured heavy metals in the present study was in the range of international standards recorded for these metals.