Several epidemiological studies link pesticide exposure to reproductive and developmental toxicity. However, additional studies have shown little or no evidence to support such relationship. On the other hand, experimental data show that some pesticides may indeed alter the reproductive function or produce birth defects (as evidenced by intrauterine death, in utero growth retardation, visceral and skeletal malformations or functional deficits) in laboratory animals. This review is a critical analysis of the epidemiological and experimental evidence available to date, that links pesticide exposure with induction of reproductive or developmental defects. Factors that must be considered when establishing a cause-effect relationship are also discussed, including the shape of the dose-response curve, exposure to pesticides in chemical mixtures and the influence of genetic background.