Bacterial endocarditis; adenocarcinoma; Streptococcus bovis; aortic valve insufficiency.We report the case of a 66 year-old female patient with infectious endocarditis due to Streptococcus bovis and adenocarcinoma of the colon that developed acute aortic insufficiency. She was submitted to aortic valve replacement surgery and later to tumor resection (right hemicolectomy). It is important to emphasize the need for complementing the study of the colon, even in asymptomatic individuals, when infectious endocarditis due to S. bovis is diagnosed. After being stabilized, she was referred to the Cardiology Infirmary for investigation. Infectious Endocarditis due toAt the time, she reported a picture of fatigue at exertion for the previous three years and a worsening of the situation for a month prior to hospitalization, associated with febrile episodes (no predilection for the time of the day), nausea and generalized arthralgia. At the physical examination, the patient was febrile, pale (+/4+), presented diastolic murmur with aortic focus and aortic accessory (+++/4+), as well as pulmonary crackles. The remainder of the physical examination was normal. Laboratory assessment: hemoglobin = 11g/dl, hematocrit = 32%, hemosedimentation velocity (HSV) = 120 mm. The chest x-ray showed enlargement of the cardiac area. The echocardiogram showed slightly increased left atrium and ventricle. The pulmonary arterial pressure was 42 mmHg. The aortic valve was thickened, with a cusp fragment projecting to the LVOT (left ventricular outflow tract) in diastole. She presented a slight MI and significant AI. The left ventricular (LV) systolic function was preserved. The transesophageal echocardiogram (Figure 1 Therapy with crystalline penicillin and amikacin was initiated even before the result of the blood cultures was available. On the subsequent days, the patient presented a good clinical picture evolution and symptom improvement without fever. She received amikacin for 14 days and penicillin for 28 days.A colonoscopy was carried out, which disclosed the presence of a sessile polyp in the transversal colon and a plane tumor at the hepatic angle (Figure 2). The histopathological analysis showed it was a well-differentiated and infiltrating adenocarcinoma.After the end of the antibiotic therapy, a new control echocardiogram showed the persistence of the significant aortic failure and the patient was referred to aortic valve replacement surgery. The surgical procedure was uneventful and the patient presented a favorable postoperative evolution, which allowed her hospital discharge on the 6 th postoperative day. The valve culture was negative.