BACKGROUND: Pulmonary arterial hypertension (PAH) can lead to significant cardiac dysfunction and is considered to be associated with an increased risk of perioperative cardiovascular complications. METHODS: We reviewed the medical records of children with PAH who under-went anesthesia or sedation for noncardiac surgical procedures or cardiac catheterizations; from 1999 to 2004. The incidence, type, and associated factors of complications occurring intraoperatively through 48 h postoperatively were examined. RESULTS: Two hundred fifty-six procedures were performed in 156 patients (median age 4.0 yr). PAH etiology was 56% idiopathic (primary), 21% congenital heart disease, 14% chronic lung disease, 4% chronic airway obstruction, and 4% chronic liver disease. Baseline pulmonary artery pressure was subsystemic in 68% patients, systemic in 19%, and suprasystemic in 13%. The anesthetic techniques were 22% sedation, 58% general inhaled, 20% general IV. Minor complications occurred in eight patients (5.1% of patients, 3.1% of procedures). Major complications, including cardiac arrest and pulmonary hypertensive crisis, occurred in seven patients during cardiac catheterization procedures (4.5% of patients, 5.0% of cardiac catheterization procedures, 2.7% of all procedures). There were two deaths associated with pulmonary hypertensive crisis (1.3% of patients, 0.8% of procedures). Baseline suprasystemic PAH was a significant predictor of major complications by multivariate logistic regression analysis (OR = 8.1, P = 0.02). Complications were not significantly associated with age, etiology of PAH, type of anesthetic, or airway management. CONCLUSION: Children with suprasystemic PAH have a significant risk of major perioperative complications, including cardiac arrest and pulmonary hypertensive crisis.