The anaerobic bacteria occurring in paddy soils sampled from fields belonging to the Rice Research Station at Ohmagari in Akita Prefecture, Japan, were surveyed from May to November, 1974. Irregularly shaped rods predominated which were found to be gram-positive, strictly anaerobic, catalase-positive and not heat-resistant; populations were estimated at 10(5)--10(-7) cells/g dry soil throughout the entire survey period. On the basis of their morphological and physiological characteristics these bacteria were identified as Propionibacterium. Most strains belonged to P. lymphophilum and P. granulosum.