No / A computer simulation based on a Monte-Carlo technique has been developed and used to investigate the influence of pellet size, dispersity, shape and aggregation on the filling of hard shell capsules. The simulations are in general agreement with experimental observations previously reported. The results also confirm recent findings that filling is a function of pellet shape and that above an aspect ratio value of 1.2 filling reproducibility is reduced. The methodology is simple and rapid in execution allowing many computer-based experiments to be performed with minimum effort.