Human beta-defensins (hBDs) are antimicrobial peptides that play an important role in the innate host defense against bacterial invasion, contribute to promotion of adaptive immune responses, and show chemotactic activities. The aim of this study was to compare the gene expression of hBD-1, -2, -3, and -4 in healthy teeth and teeth with pulpitis. Samples of healthy and inflamed dental pulps were obtained from extracted third molars and during treatment of teeth with pulpitis. Gene expression was assessed by using reverse transcriptase reaction and real-time polymerase chain reaction. HBD-2 and hBD -3 were only weakly expressed in healthy and inflamed pulps. In contrast, the expression of hBD-1 and hBD -4 was significantly increased in inflamed compared with healthy pulps. These results suggest that hBD-1 and hBD-4 might play a role in the pulpal host defense.