Think hypnotherapy can be helpful depending on the cause of stuttering. If its due to lack of confidence, I think it can be very helpful. It didnt work for me, because I think the root of my problem is more physical, although more confidence could never hurt. There is some evidence that stutterers have lesions on their basal ganglia - soft tissue calcification of a portion of the brain that controls dopamine/adenosine balance. An MRI can confirm the presence of these lesions, but in lieu of proof, the way (that I understand) that a person can work towards de-calcification is by boosting GABA and blood carbon dioxide. Hypnosis can work to help relaxation, which can boost GABA and CO2, but will largely be unhelpful in this more physical-cause (vs. psychological cause) of stuttering, but thats just my opinion, and this area of stuttering has largely been unexplored to my knowledge.