Lean applications in product development usually start with manufacturing due to the relative experience of measuring improvements and identifying wastes in physical settings. The full potential of lean implementation in any product development, however, can only be realized when applied throughout the process, starting with early process. Considering that the first and most essential principle in lean implementation is the characterization of value from the customer's perspective, it is imperative that the proper definition of value is realized at the beginning of the process. In addition, streaming and flowing of this customer's specified value should be realized throughout the process from start to finish.This paper discusses the application of lean principles to integrated design and manufacturing phases of the Product Development Process. The importance of introducing lean principles at the beginning of the product development phases for successful lean implementation is demonstrated. Two case studies are presented to demonstrate the lean application of integrated design and manufacturing phases from inception to a validated concept.