Here are some references by Scientific Experts on the use of Hypnosis to Stop Smoking: 

University of Washington School of Medicine, Depts. of Anesthesiology and Rehabilitation Medicine, Int J Clin Exp Hypn. 2001 Jul;49(3):257-66. Barber J.

Of 43 consecutive patients undergoing this treatment protocol, 39 reported remaining abstinent from tobacco use at follow-up (6 months to 3 years post-treatment). This represents a 90.6% success rate using hypnosis.
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Performance by gender in a stop-smoking program combining hypnosis and aversion. Johnson DL, Karkut RT. Adkar Associates, Inc., Bloomington, Indiana. Psychol Rep. 1994 Oct;75(2):851-7.  PMID: 7862796 [PubMed - indexed for MEDLINE]
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A field study of 93 male and 93 female CMHC outpatients examined the facilitation of smoking cessation by using hypnosis. At 3-month follow-up, 86% of the men and 87% of the women reported continued abstinence from the use of tobacco using hypnosis.
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Texas A&M University, System Health Science Center, College of Medicine, College Station, TX USA. Int J Clin Exp Hypn. 2004 Jan;52(1):73-81.  Clinical hypnosis for smoking cessation: preliminary results of a three-session intervention. Elkins GR, Rajab MH.
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Thirty smokers enrolled in an HMO were referred by their primary physician for treatment. Twenty-one patients returned after an initial consultation and received hypnosis for smoking cessation. At the end of treatment, 81% of those patients reported that they had stopped smoking, and 48% reported abstinence at 12 months post-treatment.
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Guided health imagery for smoking cessation and long-term abstinence. Wynd, CA. Journal of Nursing Scholarship, 2005; 37:3, pages 245-250.
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Study of 71 smokers showed that after a two-year follow up, patients that quit with hypnosis were twice as likely to remain smoke-free than those who quit on their own.
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Ohio State University, College of Nursing, Columbus, OH 43210, USA Descriptive outcomes of the American Lung Association of Ohio hypnotherapy smoking cessation program. Ahijevych K, Yerardi R, Nedilsky N.
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Group hypnosis sessions, evaluated at a less effective success rate (22% success) than individualized hypnosis sessions. However, group hypnosis sessions were still demonstrated here as being more effective than drug interventions.
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University of Iowa, Journal of Applied Psychology, How One in Five Give Up Smoking. October 1992.
(Also New Scientist, October 10, 1992.)
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 Hypnosis is the most effective way of giving up smoking, according to the largest ever scientific comparison of ways of breaking the habit. A meta-analysis, statistically combining results of more than 600 studies of 72,000 people from America and Europe to compare various methods of quitting. On average, hypnosis was over three times as effective as nicotine replacement methods and 15 times as effective as trying to quit alone.