Toxoplasma encephalitis (TE) is the most common manifestation of a recurrent Toxoplasma gondii infection in immunocompromised individuals, especially in AIDS patients. The infection is associated with considerable morbidity and mortality, even with improved diagnostic procedures and adequate treatment. The diagnosis of TE is difficult to establish by the demonstration of the parasite in the central nervous system or in cerebrospinal fluid (CSF). In order to diagnose TE we have developed a TGA-Dot-ELISA for antigen detection using rabbit anti-toxoplasma antiserum. We have applied this test to specimens of cerebrospinal fluid from patients with toxoplasma encephalitis (180 patients), neurocysticercosis (15), or bacterial meningitis (15). The relative sensitivity and specificity obtained for the TGA-Dot-ELISA were 0.930 and 0.730, respectively. TGA-Dot-ELISA is a promising method for the rapid diagnosis and effective prophylaxis of toxoplasma encephalitis.