A presumptive diagnosis of toxoplasmic encephalitis was made in 73 of the 428 AIDS patients followed in the Bordeaux Regional Hospital between 1985 and 1990. The sex ratio (M:F) was 2.8:1. The mean age was 36.2 years. Forty-three percent were homosexuals, 30 percent intravenous drug abusers. The encephalitis revealed the HIV infection in 10 percent of the cases; it was the first opportunistic infection in 27 percent. The clinical manifestations were: focal neurologic deficit (62 percent), fever (58 percent), headaches (47 percent), altered consciousness (45 percent), seizures (18 percent). The CT scan findings were focal lesions with (60 percent) or without (40 percent) ring enhancement. Oedema was present in 58 percent of the lesions, and multiple lesions in 59 percent. At the time of diagnosis, the mean CD4 lymphocyte count was 72 per mm3. The initial therapeutic regimens were: pyrimethamine (P) plus sulfadiazine (n = 57), P plus clindamycin (n = 11) and P plus clarithromycin (n = 5). Following acute therapy the patients had a complete (64 percent) or partial (18 percent) response, and 18 percent died. Adverse reactions were noticed in 53 percent. Sixty patients received a maintenance therapy; after a mean follow-up of 8 months, 12 relapsed and died of toxoplasmic encephalitis; 17 died of another cause. The median survival after toxoplasmosis was diagnosed was 7.5 months.