Four hundred patients with painful muscle spasm caused by five common musculoskeletal diseases were included in a double-blind controlled trial of chlormezanone, orphenadrine, orphenadrine/paracetomol and placebo. Patients were treated for one week and then asked for their subjective assessment of the treatment. Fifty-three per cent improved on placebo, 57 percent on chlormezanone, 66 percent on orphenadrine and 71 percent on orphenadrine/paracetamol. There was no significant difference between chlormezanone and placebo, but orphenadrine appeared to have a beneficial effect, presumably because of its muscle relaxant activity.