BACKGROUND AND OBJECTIVE: Isolated partial anomalous pulmonary venous connection (PAPVC) has been implicated as a cause of pulmonary arterial hypertension (PAH); however this condition is often overlooked in the diagnostic work up of patients with PH. We studied the prevalence of PAH both in patients with isolated PAPVC or associated with other congenital heart diseases (CHD) such as atrial septal defect (ASD). We also aimed to identify factors related to the presence of PAH in these patients. METHODS: We retrospectively analyzed data from the Adult CHD database at the Cleveland Clinic, U.S.A. between October 2005-2010. We included all patients diagnosed with PAPVC with or without other CHD. We excluded all patients with previous corrective surgeries. RESULTS: We identified 14 (2.5%) patients with PAPVC. Group I included patients with PAPVC (with or without patent foramen ovale (PFO)). Group II included patients with PAPVC associated with other CHD. PAH was seen in six (6/14, 42.8%) patients, two (2/7, 28.5%) in group I and four (4/7, 57.1%) in group II (P = 0.3). The mean pulmonary artery pressure in all patients (n = 14) was 29.5 ± 13.8 mm Hg. group I had a mean PAP of 23.6 ± 6.6 mm Hg as compared to 33.7 ± 16.5 mm Hg for group II (P = 0.34). The two patients in group I with PAH had either two anomalous pulmonary veins or a condition (sickle cell disease) that could potentially explain the haemodynamic findings. CONCLUSIONS: Patients with PAPVC (with or without PFO) in the absence of other CHD had normal pulmonary arterial pressure (PAP) unless they have two pulmonary veins with anomalous return or associated conditions known to cause PAH.