To evaluate a pre-thickened formula (Enfamil AR) for regurgitant gastroesophageal reflux, 104 infants were enrolled in a 5-week, multicenter, double-blind, randomized, placebo-controlled parallel group trial. The Enfamil AR group showed greater symptom reduction by the end of the first week: percent feedings with any regurgitation (p = 0.045), total regurgitation volume score (p = 0.035), and percent feedings with choke-gag-cough (p = 0.004). The most symptomatic infants at baseline had a reduction in trouble sleeping significantly with Enfamil AR by the end of the study (p = 0.030). This formula flows through a standard nipple, reduces regurgitation and choking-gagging-coughing within a week, and improves sleep in the most symptomatic babies by 5 weeks, without causing constipation.