We developed a branched corn syrup (BCS, average molecular weight: 500, content of indigestible portion: 45%) by heat treatment of indigestible dextrin with hy-drochloric acid. To confirm the safety of BCS, we conducted both an acute toxicity test and a mutagenicity test. Moreover, we observed gastroenteric effects of BCS in fifty healthy hu-mans. The results are summarized as follows. l) There was no death observed after oral ad-ministration of BCS in Sprague-Dawley-strain rats. Lethal dose (LD)₅₀ value was estimated to be more than 10 g/kg body weight. 2) No mutagenicity was observed in Salmonella typhimurium TA98, TA100, TA1535, TA1537, or Escherichia coli WP2uvrA. 3) Fifty adults were divided into five groups of ten (five of each sex) and orally administered BCS at 0.2, 0.3, 0.4, 0.5 and 0.6 g/kg body weight as indigestible portion. Although no diarrhea was ob-served in females, BCS at 0.6 g/kg as indigestible portion caused diarrhea in two out of five males. The maximum non-effective dose of indigestible portion of BCS was estimated to be 0.5 g/kg in males and more than 0.6 g/kg in females.