Fresh fecal samples from healthy volunteers were examined for their content of theLactobacillus acidophiluscomplex (LAC). A two-step isolation method for fecal lactobacilli was developed and employed in this study. Isolates of lactobacilli were identified according to their restriction fragment length polymorphism (RFLP) of genes coding for ribosomal RNA. Our results suggested that all samples contain lactobacilli and the most dominant species of h uman fecal lactobacilli isL. paracasei.In addition, several strains of LAC were recovered from specimens of volunteers. Among six LAC species, namely, Al: L. acidophilus, A2: L. crispatus, A3: L. amylovorus, A4: L. gallinarum, B1: L. gassri, and B2: L. johnsonii, isolates classified into cluster B were recovered from 6 out of 15 volunteers; however isolates of cluster A were recovered from 3 of 15 volunteers. Four of 15 volunteers had strains ofL. gasseri, 3 of them had strains ofL. johnsonii, and strains ofL. amylovoruswere also isolated from specimens of 3 of 15 volunteers. These findings suggest that group B of LAC is the predominant cluster of LAC found in human feces andL. amylovoruswas the only species of cluster A found in this study. No volunteer with blood type O had LAC in the fecalLactobacillusflora.