Abstract This paper deals theoretically with the interaction between two nonspherical cavitation bubbles in liquids by means of twin spherical expansions. Governing equations of bubble boundaries are derived by taking account of the translational motion of the bubbles in an incompressible liquid, and are exact to the order ( R i0 L ) 5 in which R i0 ( i = 1, 2) is the radii of the two bubbles and L the distance between the centers of the bubbles. The theory is extended to the case of a compressible liquid in which the compressibility effect is considered to the first order of the inverse of the sound speed in the liquid. A test computation is performed on the collapse of a single vapor bubble in the neighborhood of a plane rigid boundary and is compared with the result calculated by a fully numerical method. It is further confirmed by an experiment conducted in a water shock tube. A numerical example for the case of interaction between two nonspherical bubbles with initially different radii is also given.