Gram-negative endocarditis was uncommon in the past, accounting for 1% to 3% of cases. With the advent of antibiotics, immunosuppressive agents and narcotic abuse, the number has increased to 5% to 10% in the native valves and as high as 17% in the prosthetic valves, with Haemophilus species as the commonest aetiological agent, accounting for about 1% of the cases. We report a case of Haemophilus parainfluenzae endocarditis in a 39-year-old man who presented with heart failure and persistent fever. Echocardiography showed bi-leaflet mitral valve prolapse and severe mitral regurgitation. A small vegetation was seen at the flail anterior valve leaflet. He responded well to 4 weeks of intravenous ampicillin at 9 g/day and 2 weeks of gentamicin at 4 mg/kg/day, and subsequently underwent valve replacement.