This research investigates the effect of surfactant additives on phase inversion point in the oil-water flow in horizontal pipe. Two types of surfactants were used in the experiments; anionic type (sodium lignosulfonate (SLS)) at 200 ppm and cationic type (hexadecyltrimethyl ammonium bromide (CTAB)) at 100 ppm. The experiments were carried at mixture velocities (0.8, 1, 1.9 and 2.3) m/s. The results showed that the phase inversion points are unaffected by surfactant addition or velocity at low mixture velocities while they shifted downward at high mixture velocities. The experiments show also that anionic surfactant addition caused a forward shifting in phase inversion point and downward shifting in the addition of cationic surfactant at high mixture velocities.