We describe the first case of Moraxella lacunata definite native valve endocarditis in a patient with previously normal mitral valves. The disease was complicated with embolizations of the brain and spleen. After 6 weeks of antimicrobial treatment, valvular replacement was performed. The clinical course and diagnostic findings suggest that Moraxella lacunata possesses high aggressiveness leading to progressive valvular destruction and embolizations.