Evidence has been sought for life-prolonging effects of a variety of chemicals given subcutaneously 1 hr after intraperitoneal challenge of mice with 10(9) Staphylococcus aureus cells. The chemicals were chosen to replace chemicals found to be missing in the blood or carcass at death or to treat biochemical or visible abnormalities in sick mice near death from infection. Nafcillin given subcutaneously in adequate amounts cure S. aureus infection. In these experiments nafcillin treatment was delayed until 40% of the time from challenge to death in the controls. Chemicals were given in addition to nafcillin subcutaneously 20% of the time from challenge to death. Cortisol, Dilantic, epsilon-aminocaproic acid, glucose, nicotinamide, olive oil, phentolamine-propanalol, sodium bicarbonate, sodium lactate, and reserpine each prolonged life compared to saline treatment. When nafcillin was added, only cortisol, Dilantin, nicotinamide and reserpine were found to prolong life significantly compared to nafcillin-saline treatment Fatality rates were significantly reduced with cortisol and Dilantin when they were given in association with nafcillin compared to nafcillin-saline treatment.