Northampton have pulled out of the deal to sign Cameron Shepherd due to concerns over the Australia full-back's fitness.
Shepherd had agreed to move to the Saints on a three-year contract following the end of his Super Rugby commitments with Western Force.
However the club have now opted against bringing the 28-year-old to Franklin's Gardens following recommendation from its medical team.
"Obviously it is important to believe we will get the most out of our squad throughout the season," director of rugby Jim Mallinder told the club's official site.
"With a minimum of 32 games in Aviva Premiership Rugby, the Heineken Cup and LV= Cup, our campaign is the most demanding in the world. We obviously monitored Cameron's condition between signing his contract and his scheduled arrival and after great consideration felt that on balance we needed more certainty about his ability to handle the tough demands of our long season for the duration of his three-year contract.
"We know Cameron has ability and are confident that he will be with another club soon. But while we are disappointed that Cameron will not be joining us we are nevertheless very confident in the ability of our squad to compete in every competition this coming season.
"We have welcomed some exciting players like Ken Pisi, Dom Waldouck, GJ Van Velze and Luther Burrell to Franklin's Gardens who can offer a great deal in a number of positions. They have settled in well, bonded with the rest of the squad and worked very hard in pre-season training and we are all looking forward to the start of the season."