Alexis Neiers -- star of the E! reality show "Pretty Wild" -- was just arrested for possession of black tar heroin ... law enforcement sources tell TMZ.
We're told Neiers missed a post-jail probation meeting in November -- a probation violation -- so this morning, cops decided to pay her a visit at her L.A. home.
Law enforcement sources tell us cops searched the place, discovered black tar heroin ... and immediately placed Neiers under arrest.
Neiers -- who was released in July -- is still on probation for burglarizing Orlando Bloom's L.A. home last year ... so this new arrest could lead to some serious time behind bars.
Calls to Neiers' reps have not been returned.
UPDATE: Law enforcement sources tell TMZ, Neiers was also found with a fake Florida driver's license. All in all, she was booked on two counts -- possession of a controlled substance and perjury (for the fake ID).