This study evaluated the effects of eluxadoline, a mixed mu-opioid receptor (OR) and kappa-OR agonist and delta-OR antagonist, on cardiac repolarization. This evaluator-blinded, placebo- and positive-controlled, 4-period crossover study randomized healthy men and women to single oral doses of eluxadoline (therapeutic dose 100 mg or supratherapeutic dose 1000 mg), moxifloxacin 400 mg, or placebo. QT data were corrected using individual custom correction (QTcI). The primary endpoint was the change from baseline in QTcI intervals (Delta QTcI) between eluxadoline and placebo (Delta Delta QTcI). An upper bound of the 95% confidence interval around Delta Delta QTcI of 10 milliseconds was considered clinically significant. Concentration-QTc data were analyzed using a repeated-measures, mixed-effects linear model. Sixty-four volunteers were treated, and 58 completed the study. Assay sensitivity was demonstrated with moxifloxacin (noted by Delta Delta QTcI of 11.94 milliseconds). The maximum Delta Delta QTcI for eluxadoline 1000 mg was 4.10 milliseconds 1 hour postdose (1-sided 95% upper confidence bound, 5.81 milliseconds), and for eluxadoline 100 mg was 1.20 milliseconds at 0.5 hours postdose (1-sided 95% upper confidence bound, 2.91 milliseconds). Primary Delta Delta QTcI results were confirmed using Fridericia's formula for QTc. Categorical, morphological, and concentration-QTc analyses were consistent with the primary and secondary findings. There were no significant gender effects on Delta Delta QTcI values. The most common adverse events were contact dermatitis and nausea (12.5% each) and dizziness (10.9%); adverse events were more frequent in the eluxadoline 1000 mg group. In conclusion, eluxadoline, at therapeutic or supratherapeutic doses, did not significantly prolong QT intervals, and was safe and generally well tolerated in this study population.