Qatar is classified, according to its geographical location and climate, as a hot subtropical desert. Qatar's average annual rainfall is less than 130 mm/year (5 in). Doha, the capital of State of Qatar, is served by a collection system of groundwater and storm water which finally is disposed off into the marine water through three outfalls. In the future, another four proposed outfalls will be operating. This study aimed at assessing the impact of groundwater discharge on the receiving marine water quality. Water Samples were collected from the outfalls it themselves, Sea water from different sites around these outfalls at different distances, sea water Samples from different sites around the proposed points at different distances, and offshore samples as reference. Samples were collected during year 2007 and were analyzed physicochemically and microbiologically. Physicochemical characterization of the discharges showed that all measured parameters were complied with the environmental limits of both Qatar and GCC laws except turbidity and total suspended solids. The values of total and fecal coliform were higher than the permissible limits for Qatar and GCC environmental laws. The Physico-chemical characterization of the sea water samples collected from different sites around the discharged points recorded higher total suspended solids than the permissible limits stated by the Qatari law while the other parameters were complying with the law. Total suspended solids were higher than the permissible limits in all marine water samples while samples around the discharges points were the highest. The excess of some parameters reported by the study is due to the state urbanization and constructions activities in general. An integrated management plan must be carried out by all governmental and non-governmental authorities to protect the groundwater and avoid the deterioration of marine water quality.