Effect of photo-acoustic stimulation on the flow rate and protein concentration of whole saliva was investigated. 10 medical students' and 11 edentulous patients' salivary volume and protein concentrations were measured before, during, and after stimulation. The flow rate of the students' group was significantly higher (p < or = 0.01) before and after the treatment, whereas the protein concentration was significantly lower (p < or = 0.05) before, during and after treatment comparing to the patients' group. The flow rate of the students' groups significantly decreased during stimulation (p < or = 0.05). Salivary protein concentration of the students' group significantly increased (p < or = 0.05) after stimulation. There were no significant changes in the group of patients. Repeated stimulation combined with hypnotic relaxation was used in the case of 4 psychosomatic patients. Resting salivary flow and protein concentration significantly increased in 2 cases (p < or = 0.05) as a result of the therapy.