A method and apparatus for a mechanism for handling i/o transactions with known transaction length to coherent memory in a cache coherent multi-node architecture is described. In one embodiment, the invention is a method. The method includes receiving a request for a current copy of a data line. The method further includes finding the data line within a cache-coherent multi-node system. The method also includes copying the data line without disturbing a state associated with the data line. The method also includes providing a copy of the data line in response to the request. The method also includes determining if the data line is a last data line of a transaction based on a known transaction length of the transaction.