An initial pilot study found that caffeine ingestion had no effect on s-IgA concentration, secretion rate, or saliva flow rate at rest. Serum caffeine concentration was higher on CAF than PLA at preexercise, postexercise, and 1 h postexercise (P < 0.001). Plasma epinephrine concentration was higher on CAF than PLA at pre- and postexercise (P < 0.05). s-IgA concentration was higher on CAF than PLA at mid- and postexercise (P < 0.01), and s-IgA secretion rate was higher on CAF than PLA at midexercise only (P < 0.02). Caffeine ingestion did not affect saliva flow rate. Saliva alpha-amylase activity and secretion rate were higher on CAF than PLA (main effect for trial, P < 0.05).