Twenty persons with chronic low back pain participated in a clinical study to evaluate the effects of gravity traction. Each subject was instructed in the use of three devices, two for inversion and one for upright suspension traction. Baseline pulse and rate blood pressure were recorded before and after traction. Periods of traction did not exceed 20 minutes. The order of use of the devices was randomized. Each participant was monitored for significant side effects and was questioned to determine which device was best tolerated, easiest to use, or caused changes in back symptoms. Lateral lumbar spine radiographs were taken with the subject in the standing position and after varying periods of inversion. Observations included the following: An average increase in blood pressure of 17.2 systolic (range 4-34) and 16.4 diastolic (range 2-50) while in the inverted position. An average decrease in heart rate of 16.4 beats per minute (range, 4-32). No significant physiologic changes of blood pressure or pulse were observed in patients using GLR suspension traction; distraction of the lower lumbar intervertebral spaces (range, 0.3 to 4.0 mm) with inverted traction in all cases; side effects including periorbital and pharyngeal petechiae (one patient), persistent headaches (three patients), persistent blurred vision (three patients), and contact lense discomfort (one patient); and improvement of low back symptoms in 13 of the 16 symptomatic patients. Although these devices make lumbar traction practical in a home setting, their use should be under medical supervision because of possible side effects.