A woman was seriously injured on Monday morning with several stab wounds in the town of Trilport (Seine-et-Marne) and her ex-partner was arrested, the Meaux prosecutor said.
The 35-year-old man is suspected of stabbing his ex-partner early in the morning at the victim's home.
The victim, aged 30, is in life-threatening condition and was in the hands of doctors at midday.
On average, a femicide occurs every three days in France.