For more than a century, filamentous fungi have been used for the production of a wide variety of endogenous enzymes of industrial interest. More recently, with the use of genetic engineering tools developed for these organisms, this use has expanded for the production of nonnative heterologous proteins. In this review, an overview is given of examples describing the production of a special class of these proteins, namely chimeric proteins. The production of two types of chimeric proteins have been explored: (a) proteins grafted for a specific substrate-binding domain and (b) fusion proteins containing two separate enzymatic activities. Various application areas for the use of these chimeric proteins are described.