Sampson (knee) started a rehab assignment in the Arizona Complex League on Saturday, Maddie Lee of the Chicago Sun-Times reports.
Sampson underwent a meniscal debridement procedure on his right knee in May, and the right-hander was placed on the 60-day injured list shortly after. He'll need to make several rehab appearances before he's ready to return, but he could be an option for the Cubs sometime after the All-Star break.