The differential thermal analysis (DTA) technique is used to measure the Curie temperature of yttrium iron garnets, and of the garnets obtained by partially substituting Sm, Nd, Pr, or La for the Y. The accuracy of the method is within about 1°C. It is found that in all the above substitutions the Curie point is increased more or less linearily in the rare‐earth contents, with the largest slope for Pr, somewhat less for Nd and Sm. For La, only the compound Y2.5La0.5Fe5O12could be prepared and it did not show any measurable change from the Curie point of pure yttrium iron garnet. Two possible explanation are suggested to the increase in Curie point by Sm substitution, which does not change the magnetization of the garnet.