An interactive computer program which computes the standardized mortality odds ratio and the standardized proportional mortality ratio has been developed for use in the analysis of occupational mortality studies. The program provides flexibility in the selection of the comparison (unexposed) population, permitting both internal and external comparison, including comparison with the United States general population. Considerable control for potential confounding factors and for differences in information collection procedures can be exercised through careful choice of the comparison population. The user must select the reference cause(s) of death among 55 categories (59 for women). The condition for equivalence of the standardized mortality odds ratio and the standardized mortality ratio will be met when the selected reference cause(s) is unrelated to the exposure. The program reduces the loss of information due to sparse data during stratification by allowing the user to define the length of the age and time intervals. The program is written in Fortran IV and is designed to produce rapid, cost-efficient interactive results on any mainframe computer system.