A teatcup liner (1) which is intended for being mounted in a teatcup shell (2) comprises a tubular head portion (4) forming a passage for receiving a teat. The passage extends between a first and a second axial end of the tubular head portion. The tubular head portion has an annular lip (8), which in the mounted as well as the non-mounted state of the teatcup liner (1) extends radially inwardly from the tubular head portion. Furthermore, the teatcup liner comprises a tubular shaft portion (5), which extends from a second axial end (7) of the head portion, and a member (14), which is arranged to provide a radially outwardly directed pretension in the lip in the mounted as well as the non-mounted state of the teatcup liner (1), and is located outside said passage. A method of manufacturing such a teatcup liner comprises the steps of moulding the teatcup liner, expanding the head portion, and providing the pretensioning member.