Abstract A three‐dimensional (3‐D) transient solid–fluid coupling system has been developed in order to study cardiovascular systems and devices. The system utilized two commercial implicit solvers, which exchanged boundary parameters from separate meshes over a common interface. Facility was made for the spatial interpolation of these exchange parameters so that the solid and fluid domain meshes need not have similar density or topology. Stability algorithms were added to the iterative coupling process, as were algorithms to smooth or entirely remesh the fluid domain interior subject to the deformations imposed at the solid–fluid interface. Several application scenarios were undertaken, whereby simulation results could be compared to either analytical or detailed experimental data. It was hoped they would also offer further insight into the operation of a number of clinical devices. The results of these comparisons show that the simulation of complex cardiac systems, with non‐linear solid–fluid interactions, can now be achieved with sufficient accuracy to be of significant benefit to manufacturers. Copyright © 2002 John Wiley & Sons, Ltd.