The viability of and leakage from suspensions of Staphylococcus aureus stored in the temperature range 3 to 60 C were determined. There was a direct relationship, up to 50 C, between death and leakage, both of which increased with increasing temperature. At temperatures above 50 C, there was a different pattern of response, the total leakage being less at 60 C than at 50 C, although there was greater membrane damage at the higher temperature. Sucrose, 1 m, almost completely prevented leakage at 37 and 50 C but not at 60 C.