We report on a 8-month-old boy with AIDS, born of an asymptomatic mother with positive HTLV-III serology. He was hospitalized in the Intensive Care Unit because of anemia, fever and hepatosplenomegaly. Chest X-ray showed pneumonia and subsequent blood cultures were positive for Candida albicans. After 3 days of Amphotericin B treatment, the patient was transferred to Infectious Disease Department. After 30 days of hospitalization, the patient developed a rapid neurological impairment evolving into coma. CT scan showed a round, ring-shaped low density lesion with hyperdense and enhancing haemorrhagic centre in the left basal ganglia and a smaller hypodense lesion on the right. There was also evidence of cortical atrophy and mild ventricular dilatation. Such lesions are more commonly described in children with AIDS and congenital cytomegalic inclusion virus (CMV) encephalitis. In this case toxoplasma cysts were shown microscopically reinforcing the contention that in patients with AIDS, toxoplasma gondii infection may occur with atypical manifestation.