Biochemical analysis is adding a new dimension to the process of gene discovery. Two major developments have recently taken place in the emerging science of biochemical genomics. The first is an approach that uses a combination of tagged fusion proteins and simple pooling strategies in order to efficiently and directly assign biochemical function to the products of open reading frames (ORFs) expressed in yeast. The second is the application of metabolic profiling technologies to the study of mutant and transgenic plants. The latter approach has the potential not only to discover novel genes but also to ascribe a function to them in the context of the organism from which they are derived.