In a previous work, we have showed in mice infected with an avirulent strain of Toxoplasma gondii and receiving a didanosine treatment, an important decrease of brain cysts. It is why, the purpose of this study was to investigate the effect of didanosine treatment on AIDS patients having developed Toxoplasma encephalitis. 60 patient reports were analyzed: 22 patients (group 1) did not received didanosine in their antiretroviral treatment and 38 (group 2) were treated with didanosine. The results showed that an antiretroviral therapy was prescribed for 93 % of patients, 50 % of them received only zidovudine and protease inhibitors were prescribed for 37 %. The regimens given most frequently were those including zidovudine plus lamivudine or zidovudine plus indinavir. Among the group 1, 18 % have had a relapse of Toxoplasma encephalitis. In the group 2, 37 % of the patients suffered from one episode of TE while 16 % have had two TE after the pause in their didanosine treatment, the maximum occurring between 4 and 24 months after the pause of didanosine. This study showed that didanosine seems to have an effect on cerebral cysts. Also, this work made a synthesis about the different treatment used in AIDS patients and the new molecules yet in development against T. gondii.