MONTECODE is an interpretive program that has been written for the Ferranti Pegasus 1 computer and is in many respects similar to the normal Pegasus Autocode. It was designed in an attempt to speed up the time-consuming and complicated task of preparing Monte Carlo simulation programs. MONTECODE has been in regular use now for over two years and has enabled Monte Carlo simulations to be written in one-tenth of the time previously taken. This advantage is partially offset by an increase in computer running time but an attractive net gain has usually been experienced in practice. A worked example is given in the Appendix.