The original description (2) of Lactobacillus delbrueckii (Leichmann) Beijerinck 1901 was confused with that of L. fermentum Beijerinck 1901. Although Opinion 38 of the Judicial Commission of the International Committee on Systematic Bacteriology (16, 17) accepts L. delbrueckii as the type species, the status of L. fermentum is unclear, and the name L. fermentum has probably not been validly published. To clarify matters, the synonomy and description of L. delbrueckii (neotype strain ATCC 9649) are herein up-dated; as a corollary, we request the Judicial Commission of the International Committee on Systematic Bacteriology to issue an Opinion conserving L. fermentum and associating its concept with the description of the herein designated neotype strain of L. fermentum, ATCC 14931. As a separate matter, a number of Lactobacillus species names have been erroneously attributed to Holland (74); these citations are appropriately reviewed and corrected as follows: L. helveticus (Orla-Jensen) Bergey et al. 1925—designated neotype strain ATCC 15009, L. lactis (Orla-Jensen) Bergey et al. 1934—designated neotype strain ATCC 12315, L. bulgaricus (Orla-Jensen) comb. nov.—designated neotype strain ATCC 11842, L. plantarum (Orla-Jensen) Bergey et al. 1923—type strain ATCC 14917. Concepts associated with the above names and with L. leichmannii (Henneberg) Bergey et al.—designated neotype strain ATCC 4797, L. buchneri (Henneberg) Bergey et al. 1923—designated neotype strain ATCC 4005, and L. brevis (Orla-Jensen) Bergey et al. 1934—designated neotype strain ATCC 14869, are discussed in a modern context. Basionyms and other synonyms, author citations, descriptions of type and neotype strains, and justifications of the proposals are presented.