Danger lurks at the bathing beach for those who are hypersensitive to cold, but the danger can be eliminated by adequate desensitization. We do not pretend that, scientifically, this is the most interesting implication of the present report; we do believe that now, with summer almost at hand, it is the most immediately applicable feature of our work. The study represents a clinical and experimental investigation of twenty-two cases, seven of which have been previously reported, illustrating the various phases of hypersensitiveness to cold. This constitutes the entire group of such cases observed at the Mayo Clinic during the past ten years. The ages of these subjects ranged from 15 to 59 years. Eleven of the subjects were females and eleven were males. With few exceptions they appeared to be in good general health; some were even robust. One subject also had osteitis deformans and one a hyperfunctioning adenomatous goiter