We immunohistochemically studied the location of abnormal prion protein in the central nervous system and visceral organs at the clinical and preclinical stages of mice infected with Creutzfeldt-Jakob disease via intraperitoneal route. Abnormal prion protein was diffusely distributed in the central nervous system. The sequential study showed that its stainings were first detected 120 days after inoculation, were found in all mice after 180 days, and were the most intense and widespread after 270 days. There was no restricted involvement at the early stages nor rostrally dominant distribution of the stainings that had been found in mice infected via intracerebral route. Abnormal prion protein was also located in the follicular dendritic cells in the spleen, lymph nodes, intestinal Peyer's patch, and thymus. Its stainings were first detected in the spleen, lymph nodes, and Peyer's patch 14 or 30 days after inoculation. In the thymus, however, the stainings were first detected after 210 days in the germinal centers formed in the medulla.