Petroleum contamination of environments, which results from spillage of crude oil, is always a global concern and an ongoing threat to human health and natural environments because of its high incidence and long-term environmental impact. The aim of this study was to investigate the removal efficiency of the dry green alga Ulva lactuca biomass for biosorption of n-alkane (light and heavy) and polyaromatic hydrocarbons (PAHs) in water soluble fractions (WSFs) of crude oil from Ras El-Adabya, Suez Gulf at different time intervals (2-10 days). The physicochemical properties of water and crude oil samples were performed. Algae, which was collected from Alexandria (Abu- Qir region) between May and July 2021, was subjected to different WSFs concentrations (25%, 50%, 75%, and 100%) of crude oil by varying exposure time 2, 4, 6, 8, and 10 days. The removal efficiency of U. lactuca dry biomass was measured and monitored using gas chromatographic analysis (GC). Results showed that the concentrations of petroleum hydrocarbons (light n- alkanes, heavy n-alkanes, and PAHs) significantly decreased by increasing the contact time of the biomass to ten days, which recorded its lowest content. Removal capacity and removal percentage of U. lactuca for three types of hydrocarbons increased with increasing of contact time till it reached maximum at 10 days. Data showed that removal percentage of light n-alkanes, heavy n-alkanes and PAHs was best at 25 % of crude oil which reached 31.18 %, 17.88% and 40.57 %, respectively. Key words: Algae; Ulva lactuca; Adsorption; Crude Oil; Water Soluble Fraction; Gass Chromatograpic (GC) Analysis.