The purpose of this study was to examine salivary immunoglobulin A (s-IgA) responses to exhaustive exercise. Twenty-nine, college age (means +/- SD = 21.45 +/- 3.1 yrs; range 18-29 yrs) moderately active males (running < 10 miles per week) performed an incremental treadmill test to exhaustion. Unstimulated salivary samples, collected before as well as immediately and one hour following the test, were analyzed for s-IgA using an enzyme-linked immunosorbent assay (ELISA). Mean s-IgA levels decreased significantly (24.4%, p < 0.05) immediately following the maximal test, and remained depressed (16.9%) one hour after the test. Of the 29 subjects, five exhibited an increase (range = 1.3 to 53.3%) in s-IgA following the exercise bout. The results of this study suggest that exhaustive exercise may temporarily reduce salivary IgA levels.