A man is fighting for his life after a drug overdose at a Melbourne music festival as calls for pill testing intensify.

The man is one of two revellers who have been rushed to hospital from the Beyond The Valley festival at Lardner south-east of Melbourne.

The man, aged in his 20s, was flown to The Royal Melbourne Hospital at 7am on Monday, where he remains in a critical condition.

The other man, also aged in his 20s, was taken to Dandenong Hospital in a critical condition on Sunday. He is now listed as stable.

The overdoses follow the death of a 22-year-old man after he attended Lost Paradise music festival in NSW on the weekend.