The objective of this study was to compare efficacy of two meditation protocols for treating patients with obsessive-compulsive disorder (OCD). Patients were randomized to two groups-matched for sex, age, and medication status-and blinded to the comparison protocol. They were told the trial would last for 12 months, unless one protocol proved to be more efficacious. If so, groups would merge, and the group that received the less efficacious treatment would also be afforded 12 months of the more effective one. The study was conducted at Children's Hospital, San Diego, Calif. Patients were selected according to Diagnostic and Statistical Manual of Mental Disorders, Third Edition-Revised (DSM-III-R) criteria and recruited by advertisements and referral. At baseline, Group 1 included 11 adults and 1 adolescent, and Group 2 included 10 adults. Group 1 employed a kundalini yoga meditation protocol and Group 2 employed the Relaxation Response plus Mindfulness Meditation technique. Baseline and 3-month interval testing was conducted using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Symptoms Checklist-90-Revised Obsessive Compulsive (SCL-90-R OC) and Global Severity Index (SCL-90-R GSI) scales, Profile of Moods scale (POMS), Perceived Stress Scale (PSS), and Purpose in Life (PIL) test. Seven adults in each group completed 3 months of therapy. At 3 months, Group 1 demonstrated greater improvements (Student's independent groups t-test) on the Y-BOCS, SCL-90-R OC and GSI scales, and POMS, and greater but nonsignificant improvements on the PSS and PIL test. An intent-to-treat analysis (Y-BOCS) for the baseline and 3-month tests showed that only Group 1 improved. Within-group statistics (Student's paired t-tests) showed that Group 1 significantly improved on all six scales, but Group 2 had no improvements. Groups were merged for an additional year using Group 1 techniques. At 15 months, the final group (N=11) improved 71%, 62%, 66%, 74%, 39%, and 23%, respectively, on the Y-BOCS, SCL-90-R OC, SCL-90-R GSI, POMS, PSS, and PIL; P<0.003 (analysis of variance). This study demonstrates that kundalini yoga techniques are effective in the treatment of OCD.