The chief focus of this article is the relationship between the redox status of the host erythrocyte and that of the malaria parasite. Roles for oxidative processes in the reduced growth of malaria parasites in abnormal erythrocytes, in the host response against the parasite, and in the action of certain anti-malarial drugs are widely accepted as being established. We believe the evidence underpinning these ideas to be unacceptably deficient in a number of areas and suggest some ways in which the questions could be re-examined experimentally.