||The efficacy of trigger-point injection therapy in treatment of low-back strain was evaluated in a prospective, randomized, double-blind study. The patient population consisted of 63 individuals with low-back strain. Patients with this diagnosis had nonradiating low-back pain, normal neurologic examination, absence of tension signs, and lumbosacral roentgenograms interpreted as being within normal limits. They were treated conservatively for 4 weeks before entering the study. Injection therapy was of four different types: lidocaine, lidocaine combined with a steroid, acupuncture, and vapocoolant spray with acupressure. Results indicated that therapy without injected medication (63% improvement rate) was at least as effective as therapy with drug injection (42% improvement rate), at a P value of 0.09. Trigger-point therapy seems to be a useful adjunct in treatment of low-back strain. The injected substance apparently is not the critical factor, since direct mechanical stimulus to the trigger-point seems to give symptomatic relief equal to that of treatment with various types of injected medication.