The woman, who lives on the West side of Detroit, saw a group of men breaking into a neighbor's house on Tuesday morning. When the men spotted her, one of them fired a shot at her, a police spokesman said.
The bullet struck the underwire on the woman's bra and that saved her from a more serious injury, police said.
"It did slow the bullet down," said Detroit police spokesman Phillip Cook. "She sustained injuries but they're not life threatening."
The woman, who was not identified, was treated at a nearby hospital. The suspects in the shooting drove away.