Surfactants have been considered for enhanced oil recovery by reducing oil-water interfacial tension. This research experimentally determines the influence of surfactant concentration and formation water Salinity on oil recovery. The commercial anionic Alkyl-benzene sulphonate surfactant was used with different salinity of formation water (134.7,168.5 and187.5 g/l) respectively, and with three different surfactant concentrations (10,30 and 50g/l) . Several sand pack flood experiments were conducted using medium crude oil. Experimental results showed that emulsification becomes better with increasing surfactant concentration and higher oil recovery. The ultimate oil recoveries at 1.1 pore volume(P.V.) are 72,76.2 and 85.1% of the original oil in place(OOIP), at surfactant aqueous concentrations of 10,30 and 50g/l respectively. The effect of salinity on surfactant performance is studied and the results showed that increasing of salinity reduced oil recoveries (76.2 ,60and 46%OOIP at salinity of134.7,168.5 and187.5g/l respectively).