Aims: To investigate the association between pulmonary hypertension and mortality, length of stay and incidence of organic failure in children with pneumonia and respiratory failure. Methods: Retrospective cohort study. Patients with the diagnosis of pneumonia and respiratory failure with or without acute respiratory distress syndrome (ARDS). Interventions: none. Results: From January 2011 to November 2013, 120 children met the inclusion criteria. (89.9%) were diagnosed as having pulmonary hypertension. The overall mortality rate was 7.5%. Receiver operating characteristics (ROC) curve to evaluate the optimal threshold value of the pulmonary pressure value to discriminate patients with and without mortality yielded a value of 54mmHg (area under the ROC curve: 0,89, IC 95%). The mortality rate in patients with a pulmonary pressure greater than 54 mmHg was significantly superior compared to patients with a pulmonary pressure below this threshold value (30.0 vs. 0.77% respectively, p<0.001). The rate of renal failure and hematologic failure was significantly superior in patients with pulmonary hypertension compared to patients without it (22.0 vs. 0.0% respectively, p < 0.001), and (69.0 vs. 10.0% respectively, p<0.001). Conclusions: The incidence of pulmonary hypertension in children with pneumonia, respiratory failure and ARDS is high, and it has impact in several clinical outcomes such as mortality.