Lactobacillus spp. are universally found in the mouth, female genital tract and gastrointestinal tract of humans, as well as in many foods and health food preparations. They are generally considered to be non-pathogenic [2,3]. Large quantities of products containing lactobacilli are sold worldwide; for example, 3×106 kg of products containing Lactobacillus sp. GG (ATCC 53103) were sold in Finland alone in 1992 [2]. However, lactobacilli have been associated causally with endocarditis, meningitis, pneumonia and local suppurative conditions [4]. The case of endocarditis we report is also interesting since the source of the infecting bacteria in endocarditis is so rarely elucidated. (This case was presented as Poster M243 at The Second European Congress of Chemotherapy, Hamburg, May 1998.)