Objectives: Toxoplasmosis is a parasitic infection caused by Toxoplasma gondii (T. gondii) with various clinical outcomes. Serological tests determining IgG and IgM produced against T. gondii are widely used for laboratory diagnosis of the infection. IgG avidity test identifying the infection initiation in diagnosis is required when specific IgM antibodies are not able to be detected in early period of infection, IgM antibodies in patients with reactivation are not increased or especially in pregnant with IgM positivity. In this study, it was aimed to evaluate avidity test results and to determine the algorithmic place of this test in T. gondii infection. Methods: In this study, avidity test results requested from all of the clinics and services from serology laboratory in 1 January 2013-31 December 2013 were included. Totally, 84 anti-T. gondii IgG avidity was requested. The avidity value was researched by ELISA method using anti-T. gondii IgG avidity kit in patients included in this study. Anti-T. gondii IgG and IgM antibody tests were performed by ELISA method using commercial kit. Results: 61, 13 and 2 requests were evaluated as high avidity 72.6%, low avidity 15.5% and intermediate value 2.4%, respectively, while 8 requests were unnecessary. Conclusion: It was concluded that primarily anti-T. gondii IgG and IgM tests should be performed in suspicious cases in terms of toxoplasmosis and the IgG avidity tests should be requested from only suitable cases after the evaluation of the test results according to clinic table of the patients and/or the week of pregnancy. J Clin Exp Invest 2014; 5 (2): 246-249