Design evaluation and modification plays a critical role in the design process to develop products that meet the user requirements. Physical prototypes are commonly used to evaluate a design and justify design changes. However, physical prototypes are costly and cannot be modified. Virtual prototypes have been used but it is difficult to simulate virtual prototypes accurately and contextualize them. In this paper, a gesture-based augmented reality design evaluation system (GARDE) is presented. Using AR, GARDE is able to enjoy the benefits of both physical and virtual prototyping in design evaluation. In addition, the use of hand gestures as the main interaction input allows for interactive and intuitive design evaluation. Through the use of an off-the-shelf CAD software API, modifications of the 3D models in an AR environment can be achieved. As design evaluation is conducted in a real environment, in-situ design can also be performed using GARDE. Two case studies have been carried to demonstrate the GARDE system and are described in this paper.