South West ambulance crews say the true extent of violence they face is nearly three times higher than that recorded.
Officially, 50 Westcountry Ambulance Service staff reported incidents of physical assaults carried out against them in 2004.
But the most recent staff survey showed the actual level was much higher, with about 140 of a total of about 1,000 personnel saying they were abused.
The Westcountry Ambulance Service said it was becoming "a real problem".
Some 64% of staff said they had been subject to verbal abuse, but crews say they have to contend with many violent incidents.
One technician from Cornwall, who did not want to be identified, was recently attacked by a drunk who walked off the street and into a house where she was treating a patient.
She said: "They say they know where you live and know your family.
"If you think about these things too much you'd become a nervous wreck."
Crews have also recorded incidents including a man breaking into a Cornwall ambulance station wielding a knife, and seeing a pedestrian produce a gun from his belt and waving it at the ambulance while it was sitting at traffic lights.
Michael Willis of the Westcountry Ambulance Service said: "I think it's a real problem.
"Over the years, we've seen violence increase, especially verbal assaults, which are much more of a day-to-day issue now."
Ambulance service managers say such behaviour will not be tolerated and have pledged to do all they can to prosecute people who attack their crews.
In a guide leaflet to staff about violence, the ambulance trust said that whilst it was "committed to providing high quality patient care", it may "withdraw its services to individuals where staff may be put at risk".