Theoretical and numerical calculations are presented investigating the adequacy of the .SIGMA.(O - E)2/E approximation (Peto and Pike [1973]) when applying the Mantel/Haenszel summary chi-square statistic to the comparison of r life tables in the manner suggested by Mantel [1966], Peto and Peto [1972], and Cox [1972]. E=.SIGMA.kE(Ak), where Ak is the observation vector. Conservatism is mild unless there are marked differences in the withdrawal patterns in the r tables. Such differences may be anticipated in the case of a generalization of the life table procedure suggested by Crowley [1973], Mantel and Byar [1974], and Turnbull, Brown, and Hu [1974], wherein [human] individuals are moved from one life table to another according to changes in their treatment (or other) statuses.