The pollution of the aquatic environment with heavy metals is one of the most principal water, aquatic life, and public health problems in the Rosetta Branch. There are annual increases in pollutants and heavy metals that flow into the River Nile by many sources; as agricultural and industrial activities as well as sewage wastewater. The present study aimed to evaluate the seasonal variation of heavy metals contents (Pb, Cd, Hg, Cr, Fe, and Zn) in water and Nile tilapia fish samples, which collected from Rosetta Branch, River Nile and provide information regarding fish growth and water quality. This study was carried out along the Rosetta Branch at four sites (Kafr El-Zayat, Minyat Jenaj, Desouk, and Motobas) during 2016/2017 in four seasons. The results revealed that winter was the highest season in heavy metal concentration and summer was the lowest in heavy metals concentrations. Additionally, Kafr El-Zayat was the highest site in heavy metals concentration, and Minyat Jenaj was the lowest. In water samples, Hg was higher than the permissible limit in all season and sites. Moreover, Pb concentration was higher than the allowable limit in all seasons and sites except summer; Cd concentration was higher than the acceptable limit in autumn and winter seasons. Concerning fish samples, heavy metals concentrations in gills were much higher than that of the muscles. In Desouk and Motobas sites, the concentration of Pb in muscles was higher than the permissible limit in autumn and winter seasons. The concentration of Cd in muscles was higher than the permissible limit in autumn at Kafr El-zayat; spring season gave the highest values of HSI comparing to other seasons.