Police were called to a building on Curzon Street in Ryde about 5pm yesterday following reports of an assault.
Officers and paramedics treated an unconscious man found inside the unit.
He was taken to Royal North Shore Hospital, but was later declared dead.
Police said the man is yet to be formally identified.
A crime scene was established and an investigation is underway, with the assistance of homicide detectives, into the circumstances surrounding the man’s death.
