Sniffer dogs have found a small amount of cannabis on at least one reveller at the Big Day Out today.
Police with drug detection dogs are moving through the crowd at the popular annual music event.
Police have found small amounts of cannabis on at least one crowd member, police spokeswoman Naomi Smith said.
In 2009 teenager Gemma Thoms overdosed on ecstasy at the festival.
WA coroner Dominic Mulligan is at today's concert at the Claremont Showgrounds to get a first-hand insight into the running of the event and its facilities as part of his ongoing investigation into Ms Thoms' death.