The Tigris River is considered as one of the two major rivers in Iraq. Many factories are located on both bank of the river such as the public company for soft drinks, Al-Dura oil refinery, chemical, plastic, and leather factories, Dura electricity station, and others. It is well known that most discharge effluents into the river do not match national standard specifications. In addition, the major aim of the presented work is to assess the Water Quality Index (WQI) for the Tigris River starting from The University of Baghdad to 0.5 km downflow the confluence of the Diyala River. The samples were collected during a six months period; one sample each month for fifteen locations along the Tigris River. Different parameters were studied to calculate the water quality index: Total Dissolved Solids (TDS), NO3, Heavy Metals (Cadmium, Chromium, Lead, Zinc), and pH. The water quality index with regard to such samples is ranging between (58.24 and 160.66) and classified between poor to unfit.