Oxford youngsters Sam Long and Josh Shama have agreed new contracts with the U's.
Defender Long made six appearances last season while Shama was an ever-present for United's development side and made the bench for the final match of the season.
The pair have signed one-year deals with a further year's option available to the club.
Head coach Gary Waddock told the club's official website: "Both of them have done really well.
"Fans have seen Sam in the first team already and he has real potential as well as a fantastic attitude. Josh is a player who we have high hopes for because he has quality on the ball and works so hard for the whole 90 minutes.
"They both deserve their chance to push on, keep working at their game and build on a highly promising first year as professionals with the club."