Phage phi 80 can infect Escherichia coli in a stealthy manner and persist by forming lysogens. Such phi 80 lysogens are fairly common and often go undetected unless the host is grown at temperatures below 37 degrees C. Since low growth temperatures are required for growing temperature-sensitive mutants and often preferred for large-scale applications such as protein production, phi 80-resistant strains would be useful. We report the construction of E. coli strains that cannot be efficiently lysogenized or infected by bacteriophage phi 80. These strains contain combinations of deletions or mutations in the bacterial attachment site for phi 80 integration and/or deletions in the genes required for phage absorption to the host outer membrane. These strains should help contain and prevent phi 80 infection of E. coli cultures in a laboratory or industrial setting.