The effect of continuous (42 days) dietary administration of 5 or 20 ppm capsaicin to broiler chickens on Salmonella enteritidis susceptibility, body weight, and feed efficiency was investigated. Chickens were weighed at 1, 21, and 42 days of age. No significant differences in body weight or feed efficiency were observed. Chickens were challenged with 1 x 10(8) colony-forming units of S. enteritidis at 21, 28, or 42 days of age. The S. enteritidispositive culture rate for cecal tonsils was significantly lower (P < 0.05) in the treatment groups receiving 5 ppm or 20 ppm dietary capsaicin than in the untreated control group at all challenge times. Dietary capsaicin (5 and 20 ppm) resulted in protection against S. enteritidis organ invasion at 28 days in one experiment and at both 21 and 42 days in the other. These results indicate that continual dietary capsaicin administration increases resistance to S. enteritidis colonization and organ invasion throughout the normal growth period without detrimental effects on growth in broiler chickens.