Severe damage to six out of a total of 21 subway stations in the Kobe area during the 1995 Hyogoken-nanbu earthquake indicated a need for more attention to be given to the earthquake design of rectangular underground structures. This paper presents work undertaken to extend the present knowledge of the dynamic interaction of box-section structures with the surrounding soil, and a design method for predicting the earthquake loads on underground structures such as basement walls, tanks, subways, utility boxes, highway underpasses, and culverts.