This study assessed water quality in the northern part of the Shatt Al Arab River from Qurna to Al Jazeera Al Mohammadiyah using the River Pollution Index (RPI). Water samples were collected monthly from the six stations between October 2017 and September 2018.The RPI, calculated from the dissolved oxygen (DO), biochemical oxygen demand (BOD 5 ), total suspended solids (TSS), and ammonia nitrogen (NH 3 N), ranged from 2.25 to 5.75. The lowest RPI value was recorded at Al Shafee station in December (2.25), indicating lower pollution levels, while the highest RPI was observed at Al Jazeera Mohammedia station in April (5.75), indicating moderate pollution. The overall average RPI for t he study area was 3.55, categorizing the region as moderately polluted. Significant spatial and temporal variations in pollution levels were observed, and industrial and agricultural activities were identified as the major contributors to the pollution loa d.This study confirms the efficacy of RPI in monitoring river water quality and highlights the urgent need for targeted management strategies to address pollution in the Shatt Al Arab River.