A method, system and computer product for purging pattern history tables as a function of global accuracy in a state machine-based filter gshare branch predictor. An exemplary embodiment includes a method including storing a plurality of encountered branch instructions in the branch history table, indexing the branch history table by a branch instruction address, modifying an entry of the branch history table, indexing the pattern history table, selecting at least one of a branch history entry and a pattern history table entry as a prediction for the branch instruction, wherein the pattern history table entry is selected as the prediction for the branch instruction in response to the branch history entry being in a state specifying to use the pattern history table entry, comparing a pattern history table accuracy to an accuracy threshold, and in response to the pattern history table accuracy falling below the accuracy threshold, purging the PHT.