A 54-year-old man has been shot in the head in Yagoona in Sydney's south-west on Monday night.

Emergency services were called to Colechin Street shortly after 9pm following reports that a man had been shot.

Police and paramedics found the man had suffered a gunshot wound to his head and transported him to Liverpool Hospital where he is currently in a critical condition.

A crime scene has been established and a full investigation is now underway, police said.

Officers from Bankstown Local Area Command are investigating the circumstances surrounding the shooting and police have appealed to anyone with information to call Crime Stoppers on 1800 333 000.