Barton and Hoilett earn QPR draw
The Premier League new boys were without new signing Rio Ferdinand at Brisbane Road, and they fell behind after just 10 minutes.
Romain Vincelot glanced a superb header from Dean Cox's cross past QPR goalkeeper Rob Green to put League One club Orient ahead.
That goal was just reward for a strong start from the hosts, but a moment of top-flight quality from Hoilett - making his first appearance of pre-season - brought Harry Redknapp's side level after 19 minutes.
The former Blackburn Rovers man found some space around 25 yards from goal and gave Gary Woods no chance with a shot that arrowed into the bottom corner.
QPR began to control proceedings thereafter, but Green was forced into a fine double save to keep them level at half-time.
And Orient were undone shortly after the restart, as Barton fired home a free-kick to put the visitors into the lead.
However, Cox snatched a draw for Orient late on, as he wriggled free in the box before slotting home.