Abstract: A mixture of cultures of K88-，K99-，987P-and F₄₁-piliate enterotoxigenic E．coli was used to immunize hens to produce eggs containing antibod ies against enterotoxigenic E．coli，from which the antibodies were extracted and purified．The purified antibodies were mixed with the Chinese traditional medicine and protectives proportionally to make up the combined multivalent chicken egg-yolk antibodies ，and then produce the powder by spray drying process．In the treatment trial of infected piglets，the cure rate using the combined multivalent chicken egg-yolk antibody dry powder is higher than that of Gentamycin．In the prevention trial，the oral administration of the combined multivalent chicken egg-yolk antibodies has an higher prevention effect significantly than that of vaccine against enterotoxigenic Escherichia coli．It is concluded that the combined multivalent chicken egg-yolk antibody powder is a new．safe and effective preparation in preven．tion and treatment of piglet diarrhea caused by enterotoxigenic E．coli．