In 1991, a Roper poll of 5947 US citizens, conducted by Budd Hopkins, David Jacobs and Ron Westrum, found that 119 people (ie 2% of the sample) 'might have experienced the abduction phenomenon' as they answered yes to 4 of the questions in their survey entitled The Unusual Personal Experiences - details below.
The Unusual Personal Experiences questions:
1) Do you remember ever seeing a ghost?
2) Do you remember feeling as if you left your body?
3) Do you remember seeing a UFO?
4) Do you remember waking up paralyzed with a sense of a strange person or presence or something else in the room?
5) Do you remember feeling that you were actually flying through the air although you didn't know how or why?
6) Do you remember having seen unusual lights or balls of light in a room without knowing what was causing them?
7) Do you remember having seen, either as a child or adult, a terrifying figure-- which might have been a monster, a witch, a devil, or some other evil figure-- in your bedroom or closet or somewhere else?
8) Do you remember experiencing a period of time, an hour or more, in which you were lost, but could not remember why or where?
9) Do you remember having vivid dreams about UFO?
10) Do you remember finding puzzling scars on your body and neither you nor anyone else remembering how you received them or where you got them?
18 people of the 5947 answered yes to five of these questions which was taken to indicate they had been abducted by aliens. This could imply that 555,000 people had been abducted, however there is a margin of error on the survey of 1.4% so it could mean zero, or much more.
Note: I have tried to find a copy of this report. I can't find it anywhere - all of this information is taken from a number of websites. I will post a link to the report but I have read that it is a private report sent to 100,000 mental health experts and will never be published to the general public. If it is I will put a link to it here.
Well publicized alien abduction cases:
Betty and Barney Hill (known as The Hill Incident, or the Zeta Reticuli Incident): September 19, 1961, at around 10:30 p.m.
While driving back from a holiday in Niagara Falls, back to their home in Portsmouth, the married couple saw a rotating disk which followed them as they drove through the Franconia Notch National Park, New Hampshire. One mile south of Indian Head, the UFO descended quickly down towards them (80-100 feet above their car) causing Barney to stop on the highway. Barney got out to take a closer look and reports seeing 8-11 humanoid figures looking at him (he was looking at them in his binoculars).
Fearing that they were going to be captured, Barney ran back to the car and drove off fast. The couple felt a rhythmic series of beeping/buzzing sounds - the car vibrated and a tingling sensation ran through their bodies. A second series of beeping/buzzing sounds and they regained consciousness and realized they had continued 35 miles down the road but had no recollection of what had happened.
Under hypnosis they later report having met aliens who were blocking the road...
Returning home they observed strange personal behaviour - Betty demanded that their suitcases be left at the front door, their watches had stopped and would never run again, it is said...
Betty Hill describes her abduction experience in this clip (starts 2:12)
Betty Hill - drawing of star map allegedly given to her by aliens
Carl Sagan on the Hill Incident (Cosmos Chapter 12)
New Hampshire has marked the site of the incident with this marker:
Full account: John Fuller, The Interrupted Journey
Whitley Strieber - Sci Fi author - says he was dragged from his home by small beings and has had various subsequent meetings with, what? He does not know...
Below he tells his story to Larry King. He has written an account of his experiences in a non fiction book The Communion.
The Travis Walton Story:
November 5th, 1975 in Apache-Sitgreaves National Forest: 6 woodcutters witnessed one of their colleagues - Travis Walton - being abducted by a UFO - he floated upwards into the UFO after getting out of the truck the 7 were traveling in.
He was not found for 5 days in spite of a full police search. His 6 colleagues passed polygraph (lie detector) tests confirming their story was true at the time, it is reported. He summarizes his story here.
Linda Cortile ( Linda Napolitano ) November 30th, 1989: Linda claimed to have been beamed out of her Manhattan, New York, apartment. The incident was allegedly witnessed by Javier Perez de Cuellar and two of his bodyguards. Budd Hopkins investigated this case and claims to have been in correspondence with de Cuellar who refused requests to go public, and other witnesses.
"I'm standing up on nothing. And they take me out all the way up, way above the building. Ooh, I hope I don't fall. The UFO opens up almost like a clam and then I'm inside. I see benches similar to regular benches. And they're bringing me down a hallway. Doors open like sliding doors. Inside are all these lights and buttons and a big long table." [source]
Interview with Budd Hopkins