Splendour In The Grass attendees are being urged to be look out for meningococcal disease symptoms following the death of a Sydney man with the disease who was at the NSW music festival.
NSW Health said it had been notified of two cases in people who attended the Byron music festival from July 21 to 24.
It urged anyone with symptoms - which can include fever, neck stiffness, joint pain, a rash of red-purple spots or bruises, nausea and a dislike of bright lights - to contact a doctor immediately.
Health authorities on Thursday said a Sydney man in his 40s with the disease had died.
There have been 15 cases of meningococcal disease reported in the state this year.