The invention pertains to a rotary feed-through for supplying a fluid to a rotating machine part with a hollow shaft (3) that is rotatably supported in a housing (1, 2) and has a first sliding surface (29), with a sealing bushing (31) that is arranged in a rotationally fixed fashion within the housing (1, 2) coaxial to the shaft (3) and has a second sliding surface (30) for contacting the first sliding surface (29), and with a collecting chamber (27) that is arranged within the housing (1, 2) and serves for collecting the leakage fluid escaping between the two sliding surfaces (29, 30). The leakage fluid collected within the rotary feed-through can be monitored with the aid of a detection channel (26, 33, 34, 37, 39, 47) in the housing (1, 2) that is connected to the collecting chamber (27) and contains a leakage sensor (41).