This study was designed to investigate whether sense of humor moderates immunosuppressive effects of stress. At two time periods one and one-half months apart, forty subjects completed the Daily Hassles Scale and provided saliva samples for determining secretory immunoglobulin A (S-IgA) levels. Four scales were used to assess different aspects of the sense of humor. A negative correlation was obtained between frequency of hassles at time 1 and S-IgA levels at time 2 (r = -.32, p less than .05), suggesting an immunosuppressive effect of hassles. In support of our hypothesis, hierarchical multiple regression analyses revealed significant moderating effects of three of the four humor measures on this relationship between hassles and S-IgA. Subjects with low scores on the humor scales revealed a stronger negative relationship between hassles and S-IgA than did those with high humor scores. These results are discussed in terms of other research examining psychological influences on immune function.