Chief Vern White issued the warning Friday, saying police have found a pattern in unsolved homicides in Ottawa involving sex trade workers.
Police aren't saying how many homicides have been linked, what the pattern is or how far back it goes. But they've confirmed a link and they want the community to know, White said.
All women, especially those who work in the sex trade, should "be vigilant and exercise good safety practices," he added.
Police say they will work with social service agencies in the city to reach women who need help. Meanwhile, officers will be canvassing streets and giving safety tips to workers.
"We want to ensure the safety of people in the future and today," said White. "So for us it's about trying to give them enough information so that they can protect themselves as well and so they understand the risks."
Those who work with sex trade workers in Ottawa say they're hearing of an increase in violent dates on the street.
Workers are being told to stick to familiar dates, report bad ones and take time to think of personal safety before getting into a vehicle.
Ottawa police have also come up with handouts listing safety tips