Gram negative bacilli endocarditis are unfrequent. Nevertheless we encountered 28 cases of them (8.8%) among 320 endocarditis of which 10 were primitive and 7 cases (10.9%) among 65 prosthetic endocarditis. Bacterial species were 12 Pseudomonas aeruginosa, 2 Ps, stutzeri, 1 Ps. maltophilia, 2 Klebsiella pneumoniae, 2 Escherichia coli, 3 Serratia marcescans, 1 Enterobacter cloacae, 1 Brucella, 1 Hemophilus aphrophilus, 1 Fusobacterium funduliformis, 18 cases were hospital acquired infections related to cardiac surgery (4 cases), intracardiac catheterization (5 cases), intravenous catheter (4 cases). Uncontrolled infection or cardiac insufficiency underwent respectively in 14 and 18 cases. The overall mortality was 50 p. cent. The death occurred more frequently in primitive endocarditis (70%) than in secondary native endocarditis (45%) or prosthetic endocarditis (29%). It was also more frequent in Pseudomonas endocarditis (59%) than with other species (36%) and more frequent when cardiac sufficiency was present (50%). 15 patients underwent surgical procedure of which 6 died (40%). The results were better if the infection was cured before surgical procedures: 5 deaths occurred when the culture of the valves remained positive (9 cases) but none when it was negative. The 5 most recent cases of prosthetic endocarditis were cured. Since 1979, no death occurred among treated patients. we concluded that surgery is usually necessary but after an effective antibiotic therapy over a 4 or 6 week period.