The use of recombinant DNA technology is proving to be valuable for studies of lectin structure, biosynthesis, and function. At present, the complete primary structures of a number of plant and animal lectins have been deduced from the sequences of their corresponding mRNAs, and several laboratories are proceeding with site-directed mutagenesis studies in an effort to determine the relationship of lectin structure to function (for recent reviews see Etzler 1992; Lotan 1992). A variety of studies with transgenic organisms has been initiated to determine the factors regulating the biosynthesis of lectins and their intracellular targeting, and it is anticipated that future molecular genetic studies may greatly aid in elucidating the elusive function(s) of these molecules.