This chapter highlights fungal medicinal products, their therapeutical potential, and engineering aspects in manufacturing these products. Fungi are the sources of various known medicinal products and potential therapeutics. Although many therapeutics from fungi have been developed, many potential therapeutics from the secondary metabolites of medicinal fungi show interesting bioactivities, including antitumor, antimicrobial, antiviral, hypolipidemic, and hypoglycemic activity. The understanding of their biosynthetic pathways has allowed scientists to further improve the strains through pathway manipulation. Advanced engineering approaches, including genetic engineering and bioprocess engineering, can manipulate fungal pathways to enhance metabolite yields. A homologous gene expression system has successfully optimized the naturally occurring metabolites, such as β-lactam antibiotics in Penicillium species. A heterologous gene expression system allows strain improvement to produce new metabolites by direct alteration of the biosynthetic pathway. Optimization of fungal fermentation through engineering aspects continues to play an important role in the production of medicinal products despite the advances in the understanding of fungal physiology and biosynthetic pathways of desired metabolites. Advanced metabolic engineering technologies and tools have made the pathway engineering of fungi possible.