An 18-year-old woman has been charged with the stabbing murder of a 28-year-old man at a unit in Adelaide's north.

Police were called to the home on Frederick Street, Mansfield Park, at 5:30pm on Tuesday where the man had been stabbed.

The Mansfield Park man died at the scene.

Police said the woman, also from Mansfield Park, was known to the man.

Neighbour Stella Fahnbulleh was at home at the time of the incident.

"My son's girlfriend came running up and said 'mum, mum, wake up', and she took my phone," Ms Fahnbulleh said.

She added: "(We) rang the emergency, and the police people were asking so many questions... and I said to them 'look, someone is dying, you guys need to come quicker'.

"Within two seconds the police came, after that the ambulance. Everyone start coming."

Ms Fahnbulleh said the victim was the father of three children.

The woman was refused bail and will appear in the Port Adelaide Magistrates Court today.