Identification of cis-regulatory elements, such as enhancers and promoters, is very important not only for analysis of gene regulatory networks but also as a tool for targeted gene expression experiments. In this chapter, we introduce an easy but reliable approach to predict enhancers of a gene of interest by comparing mammalian and Xenopus genome sequences, and to examine their activity using a co-transgenesis technique in Xenopus embryos. Since the bioinformatics analysis utilizes publically available web tools, bench biologists can easily perform it without any need for special computing capability. The co-transgenesis assay, which directly uses polymerase chain reaction products, quickly screens for the activity of the candidate elements in a cloning-free manner.