Chemical genetics uses small molecules to modulate protein function and, in principle, has the potential to perturb any biochemical event in a complex cellular context. The application of chemical genetics to dissect biological processes has become an attractive alternative to mutagenesis screens due to its technical simplicity, inexpensive reagents, and low-startup costs. In vertebrates, only fish and amphibians are amenable to chemical genetic screens. Xenopus frogs share a long evolutionary history with mammals and so represent an excellent model to predict human biology. In this review, we discuss the lessons learned from chemical genetic studies carried out in zebrafish and Xenopus. We highlight how Xenopus can be employed as a convenient first-line animal model at various stages of the drug discovery and development process and comment on how they represent much-needed tools to bridge the gap between traditional in vitro and preclinical mammalian assays in biomedical research and drug development. Developmental Dynamics 238:1287-1308, 2009. (c) 2009 Wiley-Liss, Inc.