We have isolated a stable slime-negative mutant, M7, from the wild-type Staphylococcus epidermidis RP62A by mitomycin mutagenesis. Besides its inability to produce slime in the test tube this mutant differed also in two other properties from its parent strain: it lacked the ability to accumulate on a surface, and it did not produce a 115 kDa and a 18 kDa extracellular protein. In all other tested properties such as initial adherence, growth rate, cell-wall composition, surface characteristics, DNA restriction profile, the presence of a 29 kb antibiotic resistance plasmid, and antimicrobial susceptibility profile, M7 was indistinguishable from its wild-type. The mutant is an important basis for further study of the pathogenesis of polymer-associated S. epidermidis infections.