The goal of this study is to present the clinical and evolutive features of Pneumocystis infection (PCP) in infants admitted in our clinic. We summarise these aspects from 17 cases (10 male and 7 female infants), admitted between 1st January 2004 and 31st May 2005. PCP infection is rare. It represents 1,5/1000 children (17 cases of 11328 total patients) admitted in our hospital. The risk factors for PCP were age between 6 weeks and 6 months (average 3,38 months) low birth weight (average = 2428 grams), low weight for age, prolonged hospital admission (88,23% of the 17 infants were abandoned in nursery). Only one of them had HIV infection and none presented neoplastic disease. The most prominent clinical aspect was tachypnea (average 78 breath/minute, maximum 130). 16 (94,11%) had difficult breathing with chest in-drawing and flaring of ala nasi. 14 (82,35%) had generalised cyanosis. Only two (11,72%) infants had fever. Radiologic aspects were evocative, with diffuse pulmonary involvement in almost all cases (88,23%). 6 infants (35,29%) had pneumothorax and 2 (11,76%) presented pneumomediastinum. Positive diagnosis was made by microscopic examination of secretions from endotracheal tube aspiration (Grocott methenamine silver stain and Romanowsky stain). 14 infants were ventilated with a good outcome--12 surviving infants (85,7%). All infants had a full course of intravenous Co-trimoxazole. The deceased infants had more risk factors--congenital heart disease 1 case, severe cerebral palsy with organic epilepsy 2 cases. The apparent increase of PCP cases can be related to the number of abandoned children in Romanian pediatric hospitals and nurseries.