Police have issued a warning to punters heading to day two of Brownlow Hill's Secret Garden Festival today, following multiple drug detections on Friday.

A media release published by NSW police this morning reports that there were a total of a total of "28 drug detections for MDMA, cocaine, LSD and cannabis", while there were also two reports of drug overdoses. 

"Throughout the event, police will continue to target the use of illicit drugs and supply, dangerous and anti-social behaviour and alcohol-related crime," Operation Commander, Superintendent Ward Hanson said.

"Yesterday police were generally pleased with the behaviour of patrons overall however, there are still some people that continue with foolish and illegal behaviour.

"I would like to remind everyone to think twice about bringing illicit drugs into the festival, it will be intercepted by police and you will be dealt with swiftly.

"Prohibited drugs can have serious affects on your health, and lead to bad decisions that in some cases may be potentially life-threatening.

"It isn’t worth the risk."

Up to 5000 fans are expected to head to Secret Garden today where they will get to see sets from the likes of Alex Lahey, The Ruminaters and The Cactus Channel.