Thirty-one patients suffering from chronic tension headache participated in one of four procedures, each of which comprised two one-and-one-half hour sessions per week for 4 weeks. The conditions were: Chamber/Control (both weekly sessions lying on a bed in a dimly-lit room), and three active treatment procedures: Chamber/Tank, one session as above, the other floating in a dark, silent REST tank; Chamber/Relaxation, one as above, one doing progressive muscle relaxation exercises; and Tank/Relaxation, one session floating and one doing progressive muscle relaxation. By 6 months after the end of treatment, complete data had been obtained from 20 subjects. There was a significant overall decrease in headache reports; the active treatment groups collapsed improved significantly more than the control group. At the 6-month followup, the treatment groups showed continuing improvement (57% over end of treatment for the Tank-Relaxation group and a mean of 25% for the other two), whereas the control group had deteriorated by 34% since end of treatment. Clinical improvements were comparable to those of more time- and effort-consuming relaxation therapies, and confirm the usefulness of REST as a long-lasting and versatile treatment in behavioral health.