**Abstract**

*Toxoplasma gondii is a* high universal distribution intracellular parasite that causes toxoplasmosis, an infection of significant importance when pregnant women or immunosuppressed patients become infected. In immunocompetent humans, it is rarely a symptomatic disease. Diagnosis and prevention are essential to reduce severe health consequences in susceptible patients. Laboratories must play an important role in trying to avoid seroconversion, by helping in prevention and accurate diagnosis to facilitate patients' access to treatment as early as possible. The main focus of this chapter is about the steps laboratories should take in diagnosing *Toxoplasma gondii* infection by using screening tests (ELISA, HAI, AD) or confirmatory tests (Sabin Feldman dye test, ISAGA, PCR, Isolation)—determining whether patients are toxoplasmosis positive or negative—and in being actively involved in the prevention of the infection. Failing to do this would make the future of these families a very difficult road to travel.

**Keywords:** toxoplasmosis, *toxoplasma gondii* infection, seroconversion, congenital toxoplasmosis, laboratory diagnosis, ELISA, Sabin Feldman dye test, ISAGA, PCR, isolation
