The application relates to a device for feeding medical fluids, in particular for applying a pharmaceutical into the hose line of a transfer unit for enteral or parenteral nutrition. The device comprises a base body (1) having an inlet (1A) and an outlet (1B) and a rotatable closure body (2) which has an inlet (2A). The device is characterized in that the base body (1) comprises a hollow cylindrical attachment piece (4) ending in the passage (1E) of the base body between the inlet and outlet (1B, 1B), and the closure body comprises a cylindrical shut-off body (11) that is arranged in the closure body (2) such that the shut-off body (11) sits in the attachment piece (4) of the base body (1) in a sealing manner in a first position of the closure body (2), so that a fluid connection between the inlet (2A) of the closure body (2) and the passage (1E) of the base body (1) is interrupted, and does not sit in the attachment piece in a second position of the closure body, so that the fluid connection is established. In the device, the sealing is solely established in that the shut-off body of the closure body sits in the attachment piece of the base body. Thus, only one sealing surface is provided.