SIMPLTN, a computer program for the simulation of pu/se and two-dimensional NMR, is described and illustrated. The program is menu-driven and is designed to run as much like a spectrometer as possible. This approach allows a complete density-matrix calculation to be performed, yet still makes the program easy to use. SIMPLTN serves as a learning tool, and allows the design and testing of new pulse NMR methods. A spin system and a pulse program are defined, and then the program calculates an FID. The simulated data can then be transformed, inspected, and plotted using a variety of commercial NMR software packages. Systems of up to six strongly coupled spins, and almost any common liquid-state pulse program, can be simulated. SIMPLTN includes a batch mode in which simulations may be queued, and parameters may be systematically varied. This paper gives an overview of the program, some of the unique theoretical features of the program, and examples of its use.