Abstract: A tool holder releasably coupling a surgical tool such as a reaming tool to a drive shaft which tool has radially extending mounting elements. The holder includes a head portion coupled to an end of the drive shaft, the head portion having a body with an outwardly open groove extending thereacross for receiving the radially extending mounting elements on the tool. The mounting elements may be in the form of rods adapted to be received within the groove which rods extend across a base of the tool. The head portion includes a bore extending through the body in communication with the groove. A biased lock pin is slidably mounted in the bore of the head portion and is biased into a position whereby the locked pin engages the rod and locks it in place. A spring-biased lock collar is provided having stop surfaces thereon for engaging two stop surfaces on the lock pin a first locking the lock pin in the locked position and a second maintaining the lock pin in the open position.