Possible mass overdose investigated after man dies at Sydney rave

The possibility of a mass drug overdose at a music festival at Sydney Olympic Park is being investigated.

A 40-year-old man died, another person was left in a critical condition and five others were hospitalised following the Dreamstate rave last night.

The Dome at Sydney Olympic Park hosted the music festival, billed as the ultimate trance and techno experience.

Minister for Music and the Night-time Economy John Graham confirmed five people were rushed to hospital.

A possible mass overdose event was being investigated.

Dreamstate was yet to comment on the incidents in Sydney but shared a warning about high-dose MDMA capsules and pills from Victoria Health, ahead of the festival's Melbourne edition tonight.

The man who died is believed to have gone into cardiac arrest after taking illicit substances.

"This death has reignited the debate over government-run pill testing at festivals.

It wasn't offered last night but today at an event at Centennial Park it is.

Despite the weather, Laneway Festival drew in big numbers and a big police presence with drug-detection dogs working the crowd.

"It is a reminder that pill testing that has been going on is very important, has allowed information from health to be distributed," Graham said.

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