The role of cell surface in a haloresistant mechanism of S. aureus was analyzed by free-ze-etching method. Our comparative studies were carried out on S. aureus cultivated in 0.5% NaCl containing medium (Normal-Staph) and in 10% NaCl containing medium (10% -Staph), as they were or were treated with L-11 enzyme (cell wall lytic enzyme obtained from Flabobacterium sp.). 1. As shown in photographs of non-treated and enzyme-treated cells, both the cell size and cell wall thickness of 10% -Staph increased to about 1.5 times Normal-Staph. 2. When Normal-Staph was exposed to L-11 enzyme, there occurred a gradual decrease in the OD. In the case of 10% -Staph, the OD showed a down-slope with a shoulder which rose in OD once at about 10 minutes after incubation. 3. The surface pattern of plasma membrane of Normal-Staph appeared to be made up of closely arranged spherical subunits. But in the case of 10% -Staph, the spherical subunits were indistinct and appeared to be sparsely located.