Local officials said the privately-owned aircraft hit the side of a mountain in the Sestriere region, west of Turin and close to the French border.
According to Italian state television, it lost control in thick fog at an altitude of 3,000 metres (about 10,000 feet).
The TV said the pilot, a guide and four skiers were killed, while another person was injured in the crash.
Army, police and rescue teams have gone to the scene, but strong winds and low cloud is hampering rescue efforts, the French news agency AFP reported.
The craft had been flying skiers to mountains west of Turin when it lost control.
Italy's National Flight Safety Agency said that is had opened an investigation into the incident.
The helicopter belonged to the Air Service Center company, which transports skiers to the mountains and also offers flight-training programs, the Associated Press news agency reported.
The company has made no comment.
Seems to be my day of being the bad news fairy.
Ozzy
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