Pulsed-field gel electrophoresis (transverse alternating field electrophoresis system), combined with rare cutting endonucleases, was used to size the genome of five strains of lactic acid bacteria belonging to the species Lactobacillus plantarum. The sum of the fragment sizes obtained with SfiI restriction digest yielded a total value of 2700-2905 kb. Moreover, SfiI digestion gives specific patterns which could allow an intraspecific identification of L, plantarum strains. The genome sizes of Pediococcus pentosaceus, Pc. acidilactici, and Carnobacterium divergens have been estimated by this method as being 1200 kb, 1560 kb, and 3200 kb respectively.