Experimental investigations are conducted for air-water two-phase flow in horizontal helicoidal pipes of varying configurations. The helicoidal pipes are constructed by wrapping Tygon tubing around cylindrical concrete forms. Four different inside diameters of tubing and two different outside diameters of the cylindrical concrete forms are used to make the helicoidal pipe with different configurations. Also, the helix angle of helicoidal pipes varies up to 20 degrees. A total of 32 helicoidal pipes has been tested for the present study. The experiments have been performed for superficial water velocity in the range of U-L=0.008-2.2 m/s and superficial air velocity in the range of U-G=0.2-50 m/s. The pressure drop of the air-water two-phase flow is measured and the data are well correlated. It was found that the pressure drop multiplier relates strongly to the superficial velocities of air or water, and that the helix angle has almost no effect on the pressure drop, although the pipe and coil diameters have certain effects in low rates of flow. Correlation for two-phase flow in the horizontal helicoidal pipes has been established based on the present experimental data.