title: Erratum.
abstract: The levels enzyme activity given in Table 1 of the report, "Red Cell Glucose-6-Phosphate and 6-Phosphogluconic Dehydrogenases and Nucleoside Phosphorylase," by P. A. Marks [Science 127, 1338 (1958)] are incorrect by a factor of 10(3). All activity levels should read per 10(9), not 10(6), erythrocytes.