Sloshing is a potential source of disturbance in liquid storage containers. Sloshing flow in ship cargo is excited by ship motion, but the sloshing flow itself affects the ship motion in return. This paper investigates the coupling effects of ship motion with fluid oscillation inside three dimensional rectangular containers using a newly developed time domain simulation scheme. The method has been applied to a number of problems and some typical results are presented that assess the accuracy and applicability of the method. Copyright © 2009 by The International Society of Offshore and Polar Engineers (ISOPE).