Two children presenting symptoms of obsessive-compulsive disorder (OCD) and with acquired toxoplasmosis are described and the possibility of a previously rarely reported association between OCD and acquired toxoplasmosis is discussed. Case 1 is a 14-year-old boy with Tourette syndrome (TS), attention deficit hyperactivity disorder (ADHD) in partial remission and a three-year history of OCD referred to our department due to an acute deterioration of obsessive-compulsive (OC) symptoms. Case 2 is an 11-year-old boy referred to our department because of a two-year history of OCD. The OC symptoms were observed immediately following an infection. In both cases laboratory tests confirmed the diagnosis of acquired toxoplasmosis. The pharmacological therapy of T.gondi infection without any psychopharmacological treatment caused remission or significant improvement regarding OC symptoms.