This study examines the effect of 4 different types of beds on chronic low back pain patients' symptoms and signs. The beds employed were an "orthopedic" hard bed with 720 reinforced coils and a built-in bed board, a softer 500 coil bed, a standard 10 in. thick waterbed, and a hybrid bed of foam and water. Subjectively the majority of patients preferred the hard bed and felt that their back pain improved to a greater extent after 2 weeks on the hard bed as compared to the other beds. The next largest group of patients to show improvement used the waterbed. Limitations in performing the straight leg raising test coincided with the subjective complaints. Significantly improved straight leg raising was observed after use of the hard bed or waterbed in 25% of the patients using those beds. No other objective signs were altered. The 500 coil bed and the hybrid bed proved of no benefit to any patient in this study group. This limited study indicates that hard beds should remain the first choice of patients with chronic low back pain. However, if relief is not obtained for these chronic pain patients, a trial on a waterbed may prove beneficial.