There are many suggestions in the literature of the biological sciences that the pH of saliva 4 may be a valuable tool for the diagnosis and prediction of behavior. These suggestions arise from two major considerations. First, the salivary glands are dually innervated by the sympathetic and the parasyrnpathetic nervous systems and, consequently, may furnish indices of autonomic balance. Secondly, it is well known that extreme shifts in the pH of blood bring about behavioral changes ranging from tetany in alkalinosis to coma in acidosis. The blood, however, is well buffered, and minor shifts in the organism's acid-base balance do not appear in blood pH determination. Since saliva is less well buffered, it seems possible that its pH may serve as an index of the acid-base balance of the fluid matrix. Wenger's (58) recent study of Air Forces personnel supports at least the first of these two possibilities. That study showed salivary pH to be significantly related to other autonomic nervous system functions and demonstrated that it can be used to estimate autonomic balance. Such findings indicate that a review of the literature pertaining to salivary pH may be valuable.Starr (49), in his paper in 1922, presented the results of earlier investigators dating back to Donne's observations in 1833. The present review attempts to cover the work done in the field since 1922. Particular attention is devoted to recent reports which, since the advent of electrometric methods, provide the most reliable data.