We report a case of severe acute primary pulmonary toxoplasmosis in an immunocompetent young man living in Nice (Southern France). The Toxoplasma DNA extracted from the broncho-alveolar lavage fluid allowed a genetic characterization of the responsible strain which displayed an atypical genotype of Toxoplasma gondii. This unusual genetic composition of the parasite may have influenced, among other factors, the severity of the disease.