The response of the adrenal cortex to a stressor consisting of information about a surgery to be performed the following day was studied in 34 patients by monitoring changes in salivary cortisol. From those, 18 patients were subjected to an individually selected 1 h music program, applied immediately following receipt of the information, and the remaining 16 patients formed a reference group. Another 10 patients, not awaiting surgery, served as controls. Saliva was sampled before the stressor and 5 more samples were collected at 15 min intervals. The stressor produced a 50% rise in salivary cortisol within 15 min. In patients not exposed to music, cortisol levels gradually decreased but after one hour they were markedly higher than the initial level. Listening to music resulted in a marked reduction in salivary cortisol level and after one hour the relative decrease was similar to that observed in control (non-surgical) patients.