This study deals with spatial and temporal distributions of organic and inorganic phosphorus in sedimentary columns from Al-Kabir Al-Shimaliand Al-Hussain estuaries, during the period March 2013- February 2014. Organic phosphorus concentrations ranged between (2.0 - 207.6) μg/gin sediments from Al-Kabir Al-Shimali estuary, and from (1.7 –130.9) μg/gin sediments from Al-Hussainestuary. Sediment content from inorganic phosphorus ranged between (12.4 – 371.2)μg / g at sediments from Al-Kabir Al-Shimali estuary, and from (2.0 - 242.6)μg /g at Al-Hussain estuary. Granular composition of sediments did not play a significant role in the temporal and spatial distributions of organic and inorganic phosphorus. In general, organic and inorganic phosphorus concentrations decreased gradually from winter to summer, and from surface layers of the sedimentary column towards the deeper layers. The ratiobetween inorganic and organic phosphorus increasedfrom river into marine sediments. In addition, this ratio increased gradually as the sedimentdepthincreased, and was high in winter and low in summer.