Objective: With the aim of performing a completely endoscopic coronary bypass anastomosis, we have undertaken an experimental and clinical study using robotic instrumentation and voice-controlled camera guidance. Methods: The ZEUS Robotic Surgical System (Computer Motion Inc, Goleta, Calif) consists of three interactive robotic arms and a control unit, allowing the surgeon to move the instrument arms in a scaled down mode. The third arm (AESOP, Computer Motion) positions the endoscope via voice control. Phase I: In a phantom model, vascular grafts were anastomosed to the left anterior descending coronary artery (LAD) of 50 pig hearts with either 2- or 3- dimensional visualization. Phase II: In 6 dogs (FBI 20-25 kg) the left internal thoracic artery (LITA) was harvested endoscopically. Then the animals were placed on an endovascular cardiopulmonary bypass system (Port- Access, Heartport, Inc, Redwood City, Calif). Anastomosis of the LITA to the LAD was performed endoscopically with the telemetric ZEUS instruments. Flow rates through the LITA were measured by Doppler analysis. Phase III: Two patients were operated on with the ZEUS system. After endoscopic harvesting of the LITA and cardiopulmonary bypass with the Port-Access system, the bypass graft (LITA-LAD) was anastomosed endoscopically with the ZEUS system through three thoracic ports. Results: In the dry laboratory, the time range required for the robotically assisted coronary anastomosis was 35 to 60 minutes with 2-dimensional visualization and 16 to 32 minutes with 3- dimensional visualization. In the animal experiments, the median time for endoscopic harvesting of the LITA was 86 minutes (range 56-120 minutes) and for the anastomosis, 42 minutes (range 35105 minutes); flow rates through the LITA ranged between 22 and 45 mL/min. In the clinical cases, preparation times for the LITA were 83 and 110 minutes, respectively, and anastomosis times, 42 and 40 minutes, respectively. Doppler flow rates measured 125 and 85 mL/min, respectively. Both patients had an uneventful follow-up angiogram and postoperative course. Conclusions: With sophisticated robotic technology, a completely endoscopic anastomosis of the LITA to the LAD is possible, allowing technically precise operations within acceptable time limits.