AbstractHelical piles are widely used in engineering applications providing stability against compression, tension, and horizontal loads. Although the use of helical piles is increasing, the proper design and the effect of helices parameter on the ultimate load are still under investigation. This research mainly aimed to study the response of horizontally loaded helical piles, where a laboratory study is performed on physical model. Loading tests on helical piles with different helices diameters, numbers, and spacing subjected to horizontal loadings are carried out. The effects of the helix diameter, number, and spacing are monitored and a comparative study between helical piles and piles without helices is accomplished. It is worth mentioning that in general the presence of helices increases the ultimate horizontal pile capacity depending on the helices diameter, number, and spacing. It was found that the improvement ratio due to the presence of helices can reach up to 2.83 at a displacement equals 2.5% of the pile diameter.