The young Aussie has been on loan with League One side Swindon Town and was recalled when his month loan came to an end.
In his final game for Swindon against Barnsley at Oakwell he was knocked out going in for a header and has since been unavailable due to league rules which state he cannot play for two weeks after suffering concussion.
"Jamie's been back here for a while and it was just unfortunate he suffered concussion at a time when he might have been able to come in and help us," said Kevin Blackwell on the official Leeds website.
"He's got a bit more experience now and we'll see how that can help us. The main thing is it's another body in the squad."
McMaster could be in the squad for Saturday's visit to Ipswich with a place on the bench.