It happened just before 8:00 a.m. in the 2000 block of S. Simpson St.
It's not clear what lead up to the stabbing but police say the suspect and victim know each other.
The victim is only described as a woman in her 40's.
There is no word yet on an identity of the suspect.
The woman was taken to the University of Pennsylvania Medical Center where she is said to be in stable condition.