 " Greatest Hits " brought in an average of 12 @.@ 32 million American viewers , making Lost the fifteenth most watched series of the week ; this was consistent with previous Lost episodes in the same timeslot . The first half was viewed by 11 @.@ 9 million , and the audience increased to 12 @.@ 8 million in the second half . The episode received a 5 @.@ 2 / 14 in the key adults 18 – 49 demographic , placing it as the top @-@ rated scripted program for the night . In Canada , " Greatest Hits " was seen by 875 @,@ 000 people , ranking twenty @-@ seventh for the week . In the United Kingdom , the episode attracted 1 @.@ 21 million viewers , and was the second most watched program of the week on the non @-@ terrestrial channels , beaten only by Katie & Peter : The Next Chapter . In Australia , Lost was the fifty @-@ first most viewed show of the week , bringing in 1 @.@ 001 million viewers . 
