Purpose: To report a case of toxoplasma retinochoroiditis reactivation in an immunocompetent patient under atovaquone therapy. Methods: Case report. Results: A healthy woman with a history of bilateral toxoplasma retinochoroiditis since childhood presented with a reactivation of toxoplasma retinochoroiditis. Because earlier treatment regimens had either produced intolerable side effects and/or were deemed ineffective for the prevention of reactivation, the patient was started on atovaquone suspension (750 mg three times a day). After initial regression of the lesion and still under atovaquone therapy, the patient presented again five weeks later with worsened best-corrected visual acuity. Examination showed that the lesion had expanded again and more cells were present in the vitreous. Conclusions: To our knowledge, this is the first report of a reactivation of toxoplasma retinochoroiditis in an immunocompetent patient under atovaquone therapy, possibly indicating tachyzoite resistance to atovaquone.