OBJECTIVE To determine whether pulse oximetry is accurate and if it correlates with arterial blood gas saturation in pediatric patients with sickle cell anemia. METHODS Prospective, comparative study using a convenience sample of patients with sickle cell anemia who had simultaneous arterial blood gas sampling and pulse oximetry. METHODS Children's Memorial Hospital, a large tertiary care pediatric hospital in Chicago, IL. Patients selected from the emergency department and the pediatric intensive care unit. METHODS Twenty-four consecutive patients with sickle cell anemia who had simultaneous arterial blood gas sampling and pulse oximetry. RESULTS Twenty-four patients had a total of 70 simultaneous pulse oximeter and blood gas pair samples. Each patient's initial pulse oximeter/blood gas pair was used in the statistical analysis. Three patients had venous samples and were excluded from comparison, leaving 21 arterial blood gas/pulse oximeter pairs for analysis. The pulse oximeter correlated well with the cooximeter-measured arterial saturation (r(2) =.74). The pulse oximeter significantly underestimated saturation by a mean of -1.6% (95% confidence interval, -0.3 to -3; p =.03). CONCLUSIONS Pulse oximetry correlates well with cooximeter-measured saturation in patients with sickle cell anemia. Pulse oximetry significantly underestimates true arterial saturation, but the bias is clinically insignificant. Pulse oximetry can be used reliably to estimate the arterial oxygen saturation in patients with sickle cell anemia.