STUDY OBJECTIVE: To determine whether anesthesia in the presence of a mild upper respiratory infection (URI) was associated with episodes of desaturation or reactive airway problems. DESIGN: A prospective study. SETTING: Inpatient and outpatient units of a university medical center. PATIENTS: Four hundred two pediatric patients. INTERVENTIONS: Patients were monitored with continuous recordings of oxygen saturation (SpO2), capnography, and electrocardiogram. A separate anesthesiologist was present throughout each case to observe for complications and interview the anesthesia team. The decision to anesthetize patients with a URI was left to the discretion of the anesthesia team. MEASUREMENTS AND MAIN RESULTS: Thirty patients with a URI and 372 patients without one were studied. One hundred ninety-six patients were managed with endotracheal intubation and 206 with face mask; 15 in each group had a URI. There was no increase in major desaturation events (SpO2 of 85% or less for 30 or more seconds) but minor desaturation events (SpO2 of 95% or less for 60 or more seconds) were increased (p = 0.02). There was no increased frequency of laryngospasm (1 in 30 vs. 22 in 372), but there was a higher frequency of bronchospasm in intubated patients (2 in 15 vs. 1 in 181; p = 0.016). CONCLUSIONS: Children with a mild URI have an increased frequency of minor desaturation episodes, and intubated patients with a URI have an increased frequency of bronchospasm. It appears that children with a mild URI may be safely anesthetized, since the problems encountered are generally easily treated and without long-term sequelae.