Objective: To determine the relationship between primary enuresis nocturna (PEN) and obstructive upper airway problems (OUAPs). Design: Prospective, descriptive study. Setting: Tertiary care academic medical centre. Methods: Two groups of patients were included in the study. Newly diagnosed pediatric PEN patients between August 2004 and June 2005 were evaluated for OUAPs in the Department of Otorhinolaryngology of our instution and constituted the first group of patients. During the same period, patients who were on the surgery list for upper airway problems were examined for PEN in the Department of Pediatric Psychiatry as the second group. Obtained data were analyzed with regard to patient demographics and the relationship between PEN and OUAPs, and follow-up results are reported. Main Outcome Measures: There were 32 patients in each group. In the first group, 5 patients (15.6%) had totally obstructing severe septal deviation, 8 patients (25.0%) had moderate septal deviation, 10 patients (31.3%) had allergic rhinitis and inferior turbinate hypertrophy, 3 patients had adenotonsillar hypertrophy (9.4%), and 1 patient (3.1%) had septal perforation. The frequency of OUAP in PEN patients was 65.6%. In the second group, 10 patients (31.3%) had a PEN diagnosis. After at least 3 months (mean 6.3 months) of follow-up, four patients (40%) were free of PEN and two patients (20%) experienced improvement in PEN. Another four patients did not have any change in the severity of PEN. Conclusions: According to our results, OUAPs are very common in PEN patients and PEN is a common symptom of OUAPs.