The current study was conducted at three stations (Al-sibah, Alnajibiya and Almas-hab marsh) during the period from December 2020 to November 2021 along the Shatt al-Arab River. A flame Atomic Absorption Spectrophotometer (FAAS) was used to measure the concentration of some heavy metals (lead, cadmium, copper and iron) in water. The results showed seasonal changes in concentrations of heavy metals in the Shatt al-Arab River. No lead concentration was recorded by FAAS at Alnajibiya and Almas-hab marsh stations during autumn, while it was detected with a value of 0.746 mg/L at Al-siba station during autumn. In addition, cadmium was not detected by FAAS at Alnajibiya and Almas-hab marsh stations in autumn, whereas it was 0.008 mg/L at Alsiba station in winter. The highest concentration of copper was 0.319mg/ L at Al-siba station during winter, while the lowest concentration was (0.001) mg/L recorded at Alnajibiya station in spring. Iron was between 0.703 and 9.0 mg/L at Almas-hab marsh station in the winter and summer seasons, respectively. The study showed that the heavy metals concentrations in the water of the Shatt al-Arab River are arranged in the following order: iron, followed by lead, copper and cadmium.