Background. With traditional instruments, endoscopic coronary artery bypass grafting (ECABG) has not been possible. This study was designed to determine the feasibility of using a robotically-assisted microsurgical system to perform ECABG in a chronic animal model. Methods. Nine calves were placed on cardiopulmonary bypass after harvesting the left internal mammary artery (LIMA). Subxiphoid endoscopic ports (2 instrument, 1 camera) were placed, and a robotic system was used to perform ECABG between the LIMA and left anterior descending coronary artery. LIMA graft flow (LIMA(Q)) was measured. Animals were sacrificed at 1 month, and hearts underwent angiographic and histologic analyses. Results. Acute graft patency was 89% (8/9). Two animals died suddenly within the first 48 hours. There was no significant difference in mean acute and chronic (n = 6) LIMA(Q) (40.9 ± 4.7 and 38.5 ± 5.0 ml/min, respectively). Survivors had an angiographic patency rate of 100% (6/6), confirmed by histology. Conclusions. This study shows that ECABG is feasible in a chronic animal model with excellent results.