Bacteria possess many surface membrane properties, both mechanical and biochemical, that allow them to interact with their environment These properties may affect a host in either positive (beneficial) or negative (pathological) ways. All surface properties of bacteria are yet unknown therefore we attempt to increase our knowledge regarding specific strains of lactobacilli, by examining the known properties including hemagglutination and hydrophobicity. The purpose of this study was to evaluate the cell surface properties of certain strains of Lactobacillus. These strains isolated from the human vagina and gastrointestinal tract were selected because of their antagonism toward aerobic and anaerobic bacterial pathogens. Part I discusses the hydrophobicity and hemagglutination abilities of these Lactobacillus strains.