An earplug (7) for a hearing aid (1), in particular for a BTE-type hearing aid, has a front end (8) and a rear end (9). The front end (8) is adapted to be inserted into an ear canal of a wearer. The earplug (7) comprises a main body part (10) comprising a longitudinal bore (11) extending along a centrally arranged axis (A-A) of the earplug (7), and at least one sound output passage (17) in communication with said longitudinal bore (11) and leading to a sound output opening (18). The earplug also has a collar (19), which is adapted to engage the wall of an ear canal and surrounds the main body part (10). The output opening (18) has at least one edge part (18a) located in a retracted manner with respect to said front end (8).