In the analysis of stratified person-time follow-up data, the multiplicative incidence rate model requires the rate ratio homogeneity across strata. This homogeneity assumption is statistically convenient but biologically stringent. When we do not have any strong biological models on incidence rate ratio homogeneity, we cannot justify using the estimators for the common (homogeneous) incidence rate ratio without checking the assumption. Given that the homogeneity test has a low power, we at least compare two summary estimators : one based on the homogeneity assumption, and the other not. This paper proposes an equivalence test between the Mantel-Haenszel rate ratio, which is an estimator for the common incidence rate ratio, and the standardized mortality ratio (SMR), which does not require the homogeneity assumption. The proposed test gives a practical choice between these two summary measures. J Epidemiol, 1994; 4 : 133-136.