It's the good-looking teen's second weed-related arrest in less than a year.
The 18-year-old was first caught with a bottle of medical marijuana in November 2011 when he crashed his car following a night out in Hollywood.
This latest arrest is a violation of Conrad's probation for the November arrest.
According to CBS, the teen was held at a juvenile hall in LA before being released an hour later.
Conrad's older sister Paris was arrested for marijuana possession in 2010 at a football match in South Africa but charges against the socialite were dropped.
She denied reports of another drug-related arrest in France that same year.
But that doesn't mean Hiltons are above the law!
Paris famously spent 23 days in lock-up in 2007 after getting caught driving with a suspended license.
When asked about her time in jail, Paris said: "The food was horrible."
These Hilton kids just don't seem to learn from their mistakes!
