A woman has been charged with murder after a man was fatally stabbed in the neck at a Padstow home in Sydney's south-west.

The 29-year-old man was allegedly stabbed during an argument with several people at a home on Watson Road in Padstow around midnight.

Paramedics said the man was treated at the scene but died a short time later.

Detective Inspector Glen Fitzgerald said the victim was at the home with three women when a 35-year-old man arrived and a fight broke out.

"Also at the location we have established that there are three females at the place, one other male and prior to the actual incident a second male has come home," he said.

"Four of them seem to live at this address. One of the males was at an establishment with them earlier in the day."

Detective Inspector Fitzgerald said all those involved were known to each other.

A 36-year-old man and a 25-year-old woman were arrested at the scene and the woman has now been charged.

Police confirmed the victim, along with the charged woman, are Irish nationals, and said they were working with the Irish Consulate in Sydney.

The woman has been refused bail and will appear in Parramatta Local Court on Sunday.

Neighbours reported hearing screams and wailing before police arrived, and one man said his wife heard glass being smashed just after midnight.

State Crime Command's homicide squad is investigating the circumstances surrounding the death.