Viable cultures of Fusobacterium necrophorum were inoculated into the hepatic portal veins of 7 cattle. The experimentally produced hepatic necrobacillosis lesions were described from 30 minutes through 36 hours. The lesions were established by 2 different host-bacterial interactions. Most frequent, microabscesses were initiated by diffusely distributed bacteria and were observed from 30 minutes through 2 hours. Gross abscesses from 3 through 8 hours had centrally located abscess cores and were encircled by leukocytes which were predominantly neutrophils. Lesions from 12 through 36 hours had abscess cores that were encircled by leukocytes which were predominantly macrophages. Less frequent, emboli of F. necrophorum initiated infections in hepatic sinusoids or telangiectatic lesions. Hepatocytes adjacent to the bacteria exhibited coagulation necrosis and few leukocytes were observed in these lesions.