<p>This review paper critically evaluates how the design parameters of a helical pile group influence its group efficiency when axially loaded and embedded in cohesive and cohesionless soils. A thorough review of relevant research articles on the design of helical pile groups presents analytical formulas to determine the ultimate load-carrying capacity. This review concentrates on axially loaded helical pile groups under compression. It examines the effect of design parameters such as helix diameter, centre-to-centre spacing between helical piles, and the number of helixes that influence load capacity and group efficiency of helical pile group. The review demonstrates that increasing helix diameter and centre-to-centre spacing between the helical piles (optimal spacing should be twice and thrice the helix diameter for clayey and sandy soils, respectively) significantly reduces settlement and enhances the load-carrying capacity of helical pile groups. A helical pile group behaves as a single pile when the centre-to-centre spacing exceeds the optimal distance, diminishing group interaction and reducing overall efficiency. The helix diameter and spacing ratio primarily influence settlement behaviour and group efficiency, while the effect of the number of helical piles is comparatively minor. The review consolidates key design considerations for improving the axial performance and group efficiency of helical pile groups embedded in the soil.</p>