Computer modeling of mixed-mode crack propagation has rarely been attempted. This is because of the difficulty in updating the geometrical description to represent the changing crack geometry. The development of two interactive, graphical fracture propagation systems is described here. The Finite Element Fracture Analysis Program—Graphical (FEFAP-G) is a two-dimensional fracture propagation system. The BEM3D is a three-dimensional boundary element fracture propagation system. In addition, the implementation of the BEM3D analysis program in a configuration formed by an FPS-264 processor attached to a VAX-11/750 used as host computer is described. The results show that a realistic three-dimensional boundary element analysis of crack propagation is not only feasible with the aid of attached processors, but it can have its total time reduced by factors of the order of hundreds when compared to VAX alone statistics. In an example problem concerning fatigue crack propagation in a stiffened wing skin, both FEFAP-G and the BEM3D are employed to illustrate the utility of the fracture propagation systems.