"One of Us" was watched by 12.09 million Americans, ranking "Lost" as the twentieth most watched program of the week. "Lost" defeated CBS' "" by 53% among adults 18-49, the largest ever margin of victory for "Lost" over "CSI: NY" in original episodes. The ratings were also an increase over the previous episode, and improved the timeslot by 5.7 million viewers over the same night last year. "Lost" was the fifth most watched program for the week in the key adults 18-49 demographic, achieving 5.2 million viewers. In the United Kingdom, the episode attracted 1.09 million viewers, and was the second most watched program of the week on the non-terrestrial channels, beaten only by "Live FA Cup Football".