Lactobacillus endocarditis is a rare infection. In fact, only 42 cases have been described in the literature from 1938 up to date. In only 17 previously reported cases have patients been cured with medical therapy alone. Although infections produced by Lactobacillus spp, have been described in our country, none of them included endocarditis. We report herein a case of endocarditis due to a vancomycin-resistant strain of Lactobacillus casei sub. rhamnosus in a 29-year-old man with prolapse of the mitral valve. He required surgical replacement of his valve because of the poor response to antimicrobial therapy with penicillin and gentamicin. The patient displayed a successful clinical outcome, with no evidence of recurrence along the subsequent 2 years. We point out the need to accurately identify Lactobacillus spp. in isolates from blood cultures of patients with endocarditis, since these bacteria may often be mistaken for other species more frequently associated to this infection, which usually respond to conventional antimicrobial therapy. Furthermore, we suggest that early surgical replacement should be considered when lactobacillus endocarditis is diagnosed.