A woman was fatally stabbed in the neck in a Manhattan apartment Sunday night after allegedly getting into a fight with her boyfriend, sources said.

The victim, aged in her 20s, was discovered just after 5.30 p.m. after cops responded to reports of the stabbing inside the apartment on Adam Clayton Powell Jr Blvd in Harlem, according to law enforcement sources.

The woman was allegedly stabbed by her partner after they got into an argument in the apartment, law enforcement sources told The Post.

She was rushed to Harlem Hospital but was pronounced dead just after 6.30 p.m., according to cops.

The boyfriend fled the scene before police arrived.

Sources said he was wearing a black jacket, black pants and black and green sneakers at the time.

Police said no arrests had been made and their investigation was ongoing.