In this article, we present a review of the current state of metabolic engineering in Catharanthus roseus. A significant amount of research has contributed to characterization of several individual steps in the biosynthetic pathway of medicinally valuable alkaloids. However, knowledge of the regulation of these pathways is still sparse. Using hairy root cultures, we studied the responses of alkaloid metabolism to environmental stimulation such as light and elicitation. Through precursor feeding studies, the putative rate-limiting steps of the terpenoid pathway in hairy root cultures also have been examined. Relating this knowledge to specific events at the molecular level, and the cloning of corresponding genes are the next key steps in metabolic engineering of the C. roseus alkaloids.