In this study, we investigated the distribution of lesions and protozoa in LWD piglets inoculated orally with oocysts of Toxoplasma gondii (Strain O-1) isolated from a cat. Infected piglets developed fever, diarrhea, dyspnea and loss of appetite. They were euthanatized at 8 and 10 days after the inoculation. Histologically, necrotic and nonsuppurative inflammatory lesions were observed in many different organs, more severely in the lymph nodes, thymus, spleen, stomach, intestine, adrenal gland, pancreas, lungs and liver. Minor lesions were observed in the bone marrow, tongue, heart, skeletal muscles, spinal cord and brain. Using an immunohistochemical staining technique, we were able to confirm the presence of tachyzoites in all of the above-mentioned organs as well as some other organs that were characterized by an absence of necrotic lesions such as the salivary glands and kidney.