The present dissertation was planned to evaluate the reproductive toxicity of certain biorational pesticides i.e. Vertimec and a formulation of the bacterial bioinsecticide Bacillus thuringiensis, that are recommended universally and in Egypt to control various economic pests. The organochlorine insecticide, DDT was introduced for comparison. Experiments were carried out on Japanese quail birds and white albino rats. Weights of sex organs, and their histopathological examination; spermatozoal morphology, concentrations of certain sex steroidal hormones and female productivity, were investigated. This book is useful to all the stakeholders of plant protection. All the concerned researchers, scientific community, institutions and NGOs.