Abstract: Three hundred and thirty 1-day-old AA broiler chickens were randomly allocated to three groups for 5 replicates with 22 broliers each, and fed a commercial starter diet and the same diets supplemented with 1,000U/kg (250mg/kg), 9,000U/kg (2250mg/kg) of α-amylase preparation up to 7 day of age, followed by three-week removal of amylase, to investigate possible carry-over effects of short-time enzyme supplementation on the development of digestive organs and intestinal enzyme activities. The results showed: there was no apparent effect of supplementary amylase on relative weights of liver, gizzard, proventriculus, relative length of small intestine, and the activities of amylase and protease in small intestinal contents. The relative weight of small intestine, however, increased by 4.2%~47.6% on day 7, by 5.4%~34.0% (P<0.05) and 13.8%~20.4% after 3 days (day 10) and 7 days (day 14) removal of dietary amylase, respectively. On day 21, all the parameters of digestive organs remained paralleled. A significant depression of intestinal amylase activity of all experimental groups were observed after 7 day removal of dietary amylase. The activity of intestinal protease was unaffected in all periods. These results implied that exogenous amylase had a carry-over effect on the endogenous enzyme activity in broilers.