Carol's pick:
Sherman KJ, Cherkin DC, Erro J, Miglioretti DL, Deyo RA. Comparing yoga, exercise, and a self-care book for chronic low back pain: a randomized, controlled trial. Ann Intern Med. 2005 Dec 20;143(12):849-56. PMID: 16365466
The title is a bit misleading, since the article talks about exercise developed by a physical therapist. In my book, that makes it yoga compared to physical therapy. The study compares the back pain and function after 12 once-a-week 75 minute classes. The classes were in the viniyoga tradition. "RESULTS: After adjustment for baseline values, back-related function in the yoga group was superior to the book and exercise groups at 12 weeks (yoga vs. book: mean difference, -3.4 [95% CI, -5.1 to - 1.6] [P < 0.001]; yoga vs. exercise: mean difference, -1.8 [CI, -3.5 to - 0.1] [P = 0.034]). No significant differences in symptom bothersomeness were found between any 2 groups at 12 weeks; at 26 weeks, the yoga group was superior to the book group with respect to this measure."

Other Research
Galantino ML, Bzdewka TM, Eissler-Russo JL, Holbrook ML, Mogck EP, Geigle P, Farrar JT. The impact of modified Hatha yoga on chronic low back pain: a pilot study. Altern Ther Health Med. 2004 Mar-Apr;10(2):56-9. PMID: 15055095

Greendale GA, McDivit A, Carpenter A, Seeger L, Huang MH. Yoga for women with hyperkyphosis: results of a pilot study. Am J Public Health. 2002 Oct;92(10):1611-4. PMID: 12356608

Luskin FM, Newell KA, Griffith M, Holmes M, Telles S, DiNucci E, Marvasti FF, Hill M, Pelletier KR, Haskell WL. A review of mind/body therapies in the treatment of musculoskeletal disorders with implications for the elderly. Altern Ther Health Med. 2000 Mar;6(2):46-56. PMID: 10710803

Mehling WE, Hamel KA, Acree M, Byl N, Hecht FM. Randomized, controlled trial of breath therapy for patients with chronic low-back pain. Altern Ther Health Med. 2005 Jul-Aug;11(4):44-52. PMID: 16053121 (Conclusion: Patients suffering from chronic low-back pain improved significantly with breath therapy. Changes in standard low-back pain measures of pain and disability were comparable to those resulting from high-quality, extended physical therapy.)

Williams KA, Petronis J, Smith D, Goodrich D, Wu J, Ravi N, Doyle EJ Jr, Gregory Juckett R, Munoz Kolar M, Gross R, Steinberg L. Effect of Iyengar yoga therapy for chronic low back pain. Pain. 2005 May;115(1-2):107-17. PMID: 15836974