The textbooks say no, but estimate that well over 95 percent of the population can be hypnotized in a therapeutic setting with someone they trust. Because hypnosis is a state that requires focused attention, not everyone can be hypnotized. The very young (under the age of three), those with conditions that impair the ability to concentrate (such as organic brain damage), those with an extremely low IQ, those who are intoxicated or are on high doses of legal or illegal drugs may not be able to be hypnotized. Finally, I would add that anyone who does not want to be hypnotized cannot be hypnotized. Hypnosis is a cooperative state and therefore requires permission to produce AND maintain the state.
Having said that, I have never yet met anyone who wanted to be hypnotized in my office not enter the hypnotic state. I have seen people who have only allowed themselves to enter light hypnotic states, usually due to fear of loss of control. Fortunately, all that is needed to produce therapeutic change using hypnosis are the lightest states.