The aim of this study was to determine whether measuring salivary chromogranin A (CgA) is useful in assessing individual stress levels and whether bruxism-like activity influences the salivary CgA level. From 44 adult healthy volunteers, we collected saliva samples with and without a stress condition (loud unpleasant sound). We assayed salivary samples with an ELISA to determine the content of CgA. We investigated also the effect of bruxism-like activity on salivary CgA production during stress. There were three patterns (group A, B, C) of response to the stressor on salivary CgA. They showed different responses and different effects of bruxism-like activity. This study shows the possibility of evaluating stress levels of individuals by measuring salivary CgA. Salivary CgA responds to psychosomatic stress. Bruxism-like activity prevented a stress-induced increase of salivary CgA in group A and B (75% of subjects), suggested that the reaction of the sympathetic-adrenomedullary system is regulated by the bruxism-like activity of the masticatory organ. The effect of bruxism-like activity in group C (high baseline of salivary CgA) was different from the effect in group A and B.