BACKGROUND Achromobacter xylosoxidans is a ubiquitous environmental gram-negative bacterium, very resistant to antibiotics. Endocarditis caused by these bacteria is extremely rare, with only 20 cases described in the literature to our knowledge. Mortality rates are high, and treatment usually involves a combination of antibiotics and surgery. Nosocomial infections predominate with a strong association between bacteremia and immunosuppression. CASE REPORT A 19-year-old immunocompetent male presented with endocarditis He had interatrial and interventricular communication corrected at age 11 months and aortic coarctation correction at age 10. Initial echocardiogram showed a possible interventricular patch infection, which was later ruled out. He was treated initially for endocarditis with a combination of antibiotics, but because he remained febrile after appropriate antibiotic treatment, surgery was performed. The patient had a favorable outcome after surgery and was asymptomatic on follow-up. CONCLUSIONS Endocarditis caused by A. xylosoxidans is extremely rare. To date, only 20 cases of IT have been reported in the literature, of which only two involved a native valve. Given the scarcity of cases reported, there is no consensus on the best treatment.