Pneumocystosis is well known as an opportunistic infection that is presently most frequently registered in patients with HIV infection and in those with other immunodeficiency states. Earlier, after the Second World War, Pneumocystis pneumonia was most commonly detected in debilitated and premature children; nosocomial outbreaks of pneumocystosis were studied in detail in the 1960s and 1970s. The pathogen is transmitted through the air, but a number of references indicate that it can be transmitted through the placenta. Despite the increasing number of publications on pneumocystosis in pediatrics, physicians remain unfamiliar with this disease. The paper provides evidence that Pneumocystis jiroveci can infect the fetus in utero. If unrecognized, the disease can lead to a child’s death due to severe respiratory failure. The authors describe their case of generalized pneumocystosis that has developed in a child with evidence of intrauterine infection (detection of the pathogen in the autopsy material and placenta and identification of serological markers in his/her parents). The issues that are associated with intrafamilial infection and a risk for in utero transmission of P. jiroveci are discussed.