Two kinematically dissimilar robots for laparoscopic surgery have been designed and built through a collaborative effort between IBM Research and the Johns Hopkins University School of Medicine. The two mechanisms represent two distinct design approaches and a number of different engineering design decisions. In this paper we describe the mechanical design and kinematic structure of the two robots and report on the results of laboratory evaluations of the two mechanisms. The two systems are compared in terms of safety, ergonomics, ease of control, accuracy, and mechanical stiffness. In each of the categories we attempt to separate the impact of the particular design decisions made in the construction of each mechanism from the more general issue of the fundamental potential and limitations of each of the design approaches towards satisfying the particular design criterion. Based on our experience, we offer some conclusions and recommendations regarding the design of surgical robots for laparoscopy.