ORIENT have missed out on a first round bye in the Johnstone's Paint Trophy.
16 clubs received byes in Friday's pre-draw, but Orient will join the competition at its earliest stage.
The opening round is divided into four regional groups, and Orient's potential opponents are Brentford, Brighton & Hove Albion, Charlton Athletic, Dagenham & Redbridge, Gillingham, Southend United and Stevenage Borough.
The first round draw will take place live on Sky Sports' Soccer AM programme on Saturday August 14, with the ties due to be played in the week commencing August 30.
Orient progressed to the southern section quarter finals last season, losing on penalties to Hereford United after defeating Brighton & Hove Albion - then managed by Russell Slade - in the second round.
Full regional groupings
Southern Section - East
Brentford
Brighton & Hove Albion
Charlton Athletic
Dagenham & Redbridge
Gillingham
Leyton Orient
Southend United
Stevenage
Southern Section - West
AFC Bournemouth
Aldershot Town
Exeter City
Oxford United
Southampton
Swindon Town
Torquay United
Yeovil Town
Northern Section - East
Chesterfield
Hartlepool United
Lincoln City
Northampton Town
Notts County
Rotherham United
Sheffield Wednesday
Walsall
Northern Section - West
Accrington Stanley
Macclesfield Town
Morecambe
Oldham Athletic
Port Vale
Rochdale
Shrewsbury Town
Tranmere Rovers
Byes - Southern Section
Barnet
Bristol Rovers
Cheltenham Town
Colchester United
Hereford United
Milton Keynes Dons
Plymouth Argyle
Wycombe Wanderers
Byes - Northern Section
Bradford City
Burton Albion
Bury
Carlisle United
Crewe Alexandra
Huddersfield Town
Peterborough United
Stockport County
