Pesticide-induced oxidative stress as a possible mechanism of toxicity has been a focus of toxicological research for the last decade. Yet for certain pesticides, mechanisms leading to oxidative stress are only partly understood. Pesticide-induced oxidative stress is the final manifestation of a multi-step pathway, resulting in an imbalance between pro-oxidant and antioxidant defense mechanisms. Concomitantly, pesticide intoxication induces a derangement of certain antioxidant mechanisms in different tissues, including alterations in antioxidant enzymes and the glutathione redox system. In this article, we discuss the impact of certain factors that are important in the potentiation of pesticide-induced oxidative stress, immunotoxicity, and apoptosis. Understanding risk factors largely depends upon the cellular and molecular events underlying pesticide-induced stress in experimental animals. These factors must be considered in the safety/toxicity evaluation of any pesticide. The identification and characterization of plant products/drugs might be helpful for understanding the mechanisms of compensation and repair that are due to oxidative stress-induced injury. This paper reviews the nature of such damage, the cellular conditions in which it occurs, and oxidative-stress data that may be applied to the development of risk-assessment methods and models that are designed to reduce some of these uncertainties.