Distribution and variation of bacitracin synthetase gene (bac) sequences in 22 laboratory stock strains of Bacillus licheniformis were studied by Southern hybridization of bac gene probes from B. licheniformis ATCC 10716 to genomic PstI or Hind111 restriction fragments. Eleven Strains gave hybridization signals. These hybridization patterns were classed into two types, Eight strains Showed similar patterns to that of ATCC 10716 and all, except one, produced bacitracin. The three Strains showed fairly different hybridization patterns from that of ATCC 10716, and one (ATCC 33632) of them produced bacitracin. None of the remaining 11 strains. including ATCC 14580 (type strain), gave any hybridization signals, All strains carrying bac gene sequences were erythromycin resistant. With one exception. all strains without bac gene sequences were erythromycin sensitive. These results show that B. licheniformis strains are divided into two groups with respect to presence of bac gene sequences and erythromycin resistance.