UPDATE: Police have charged a 20-year-old George Town woman with murder for allegedly fatally stabbing her partner at their George Town home this morning.
The 21-year-old man allegedly received one stab wound after an altercation at the Agnes Street home about 1.45am.
He died at the Launceston General Hospital.
Forensic police are examining the house this morning.
Neighbours say the couple had been in an on-off relationship for at least two years, and had moved into the Agnes Street home with their young son just over one year ago.
Both were known to police.
The man is the sixth person to be allegedly murdered in Tasmania in the past two months.
Inspector John Ward will hold a press conference at Launceston Police Station at 4pm today.