A total of 2, 490 South American Indians affiliated with 10 tribes were studied for esterases A1, A2, A3, B, D, and carbonic anhydrases 1 and 2. Wide variation was observed in the prevalence of ESD1, the extreme values being 0. 44, encountered among the Xikrin, and 0. 95, found among the Cashinawa. Seven of the 10 frequencies fell within the interval of 0. 66–0. 87. These results were integrated with those of earlier surveys. In a general way we observe lower values in the eastern and Atlantic Coast groups, but this is mainly due to the low frequencies found among the Gê tribes and the Caingang, who speak a language which has many affinities with Gê. High prevalences were observed among the tropical forest tribes. A fair amount of intervillage, intratribal variation was found among the Ticuna and Caingang. No variability was detected in the A1, A2, A3, B esterases. In the carbonic anhydrases we confirmed the presence of a “private polymorphism” among the Baniwa.