This review covers the highlights of combinatorial biosynthesis applied on post-polyketide synthase modifying enzymes, such as oxygenases, ketoreductases, glycosyl- and methyltransferases, acyltransferases, halogenases, cyclases and aminotransferases. Since this is the first review on this topic, it covers literature from 1985 to 2002, and 248 references are given.