This study describes the molecular typing of Pneumocystis jiroveci organisms from 5 nonpremature immunocompetent infants who developed a primary infection. Four P. jiroveci internal transcribed spacer (ITS) types were identified. All have been previously described in reports concerning immunosuppressed adults with pneumocystosis. Present data suggest that identical types can be implicated either in first contact or in additional contacts between fungus and host and that both immunocompetent infants and immunocompromised patients may be part of a common human reservoir for the fungus.