The 57-year-old employee, who had worked at the winery for eight years, was not breathing when he was found unconscious near one of the bottling lines just after 4.30pm.

Paramedics were called to the site and treated the man for cardiac arrest.

NSW Ambulance Service Inspector Markus Zarins said there were no visible signs of trauma but the man was pronounced dead on arrival at Griffith Base Hospital.

Griffith police also rushed to the site and a crime scene was established, which Inspector Tony Reneker said was standard practice for any fatality.

In a statement from Casella Wines, a spokeswoman said the company was mourning the sad loss of a colleague.

"The much loved and respected team member will be missed by all who knew him," she said.

"The passing of our colleague is understandably upsetting for all and our thoughts and prayers are with his family at this time."