Perhaps the biggest example of dramatic irony within The Cask of Amontillado is the overall plot in and of itself: Montresor is planning on killing Fortunato, which we learn at the beginning of the story, though Fortunato is under the impression that he is on his way to test the validity of a non-existent barrel of amontillado. But there are still smaller parts within the plot that also exhibit dramatic irony, such as when Montresor repeatedly says that they should turn back because of Fortunato's health, which we know is the opposite of what Montresor actually wants. Also, Montresor gives Fortunato a couple of drinks of alcohol from his stores on their way down to the end of the vaults, telling Fortunato that is to "defend [them] from the damps", but in reality he is simply trying to keep Fortunato too drunk to fight back; he even goes so far as to say that he drinks to Fortunato's long life.

Dramatic irony always adds something to a reader's experience. In this case, it is suspense as we ask ourselves: When will Fortunato find out what Montresor's true intentions are? Will Fortunato find out? Or will he just fall victim to Montresor's revenge without knowing it? The story is fairly short, so we don't have long to wonder about Fortunato's fate, but while we read, we do find ourselves wondering about how everything will end.