Novel tools for existing robotic surgical systems present opportunities for exploring improved techniques in minimally invasive surgery. Specifically, intraoperative ultrasonography is a tool that is being used with increased frequency, yet has limitations with existing laparoscopic systems. The purpose of this study was to develop and to evaluate a new ultrasound system with the da Vinci® Surgical System (Intuitive Surgical Inc., Sunnyvale CA) for laparoscopic visualization. The system consists of a prototype dexterous laparoscopic ultrasound instrument for use with the da Vinci surgical system, an integrated image display, and navigation tools. The system was evaluated by surgeons during pertinent activities, including phantom lesion detection and needle biopsy tasks, as well as in vivo porcine visualization and manipulation tasks. The system was found to be highly dexterous, clinically desirable, and advantageous over traditional laparoscopic systems. This device promises to improve performance of complex minimally-invasive surgical procedures.