Abstract: A pile with fins is a newly developed pile foundation, which is capable of supporting large applied torques. The torsional resistance of the pile with fins is mainly supplied by the fins mounted along the pile shaft and at the bottom of the pile, which is quite different from a circular pile in the load transfer mechanism. Large-scale model tests are performed to investigate the differences between a circular pile and a pile with fins. It is found that the fins on a pile change the applied torque-twist angle curve from a steep drop type to a slow change type and improve the torsional resistance of the pile up to 4.7 times. To investigate the effect of piles with fins on pile groups subjected to eccentric lateral load, a 1?2 pile group with spacing of 3 times the diameter is analyzed using a software GROUP. It is found from the numerical results that the maximum pile-head torsion and bending moment decrease by 30% and 79% respectively as the piles with fins are employed in the group.