They went down 3-0 to Championship high-flyers Leeds United to exit the competition.
David Lowndes was on hand as ever to take these pictures of just some of the fans there.
Take a look and see who you know.
Get more Posh news, here.
21. Posh 0 Leeds 3
Peterborough United fans watch their side fall to a 3-0 defeat to Leeds United. Photo: David Lowndes
22. Posh 0 Leeds 3
Peterborough United fans watch their side fall to a 3-0 defeat to Leeds United. Photo: David Lowndes
23. Posh 0 Leeds 3
Peterborough United fans watch their side fall to a 3-0 defeat to Leeds United. Photo: David Lowndes
24. Posh 0 Leeds 3
Peterborough United fans watch their side fall to a 3-0 defeat to Leeds United. Photo: David Lowndes
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