Assays for superoxide dismutase (SOD) and catalase (CAT) activities are widely employed to indicate antioxidant responses underlying the toxic effects of test chemicals. Yet, earlier studies mainly described the procedures as performed according to manufacturer’s instructions without modifications that are specific to any organisms. The present protocol describes the steps in analyzing the superoxide dismutase (SOD) and catalase (CAT) activities in C. elegans, which is a model organism that can be used to study effects of pharmaceutical compounds and environmental pollutants. The main steps include: (1) sample preparation; (2) total protein assay; (3) SOD activity assay; (4) CAT activity assay; and (5) medium list and formula, and also data analysis and performance notes.