With the discovery of combinatorial chemistry, high-throughput screening, chemical genetics, chemoinformatics and gene expression profiling, huge number of synthetic compound libraries have generated and the pace of discovery and screening of pesticides has dramatically escalated significantly and have become modern tools in the burgeoning field of agrochemicals. Today, automated procedures allow more than 5 lakhs of compounds to be screened per year under in-vivo high-throughput screening, which is invaluable in the search for new leads. Natural products from microbes and plants offer a broad array of lead molecules with great diversity in their structures and biological activity. Screening methods for active constituents include bioassay-guided isolation, fractionation-driven bioassay, isolate and assay, and with increasing exploitation of lead based biochemical combinatorial chemistry approaches. The contribution of biorational design is continuously rising to identify novel mode of action in the discovery process. These developments will prompt the agricultural chemists to take a new look at the way chemistry was traditionally done in the laboratory. The objective of this review article is to elaborate different screening procedure for development of new pesticides.