The rate of Toxoplasma gondii seropositivity in patients diagnosed with pediatric obsessive compulsive disorder (OCD) is investigated. Toxoplasma avidity levels, antitoxoplasma IgG, and antitoxoplasma IgM are investigated using the enzyme-linked immunosorbent assay (ELISA) method to examine the serums of 42 patients diagnosed with OCD (DSM-IV criteria) and 45 healthy individuals in the control group. Anti-toxoplasma IgG seropositivity was found in two patients (4.8%) among the pediatric OCD cases. Anti-toxoplasma IgM seropositivity was not detected in any patient. The toxoplasma avidity levels in patients determined to have anti-toxoplasma IgG seropositivity were 35 +/- 7.07. In the control group, however, antitoxoplasma IgG seropositivity was detected in four (8.9%) children. However, antitoxoplasma IgM seropositivity was not detected in any of the children, and the toxoplasma avidity level was 33 +/- 2.44. No statistically significant difference was found between the OCD group and the control group in terms of anti-toxoplasma IgG, anti-toxoplasma IgM seropositivity, and toxoplasma avidity level (p > 0.05). The results of our study indicate that toxoplasma infection has no major role in the etiology of pediatric OCD. (C) 2015 Elsevier Inc. All rights reserved.