Objectives : To demonstrate the need for differential diagnosis between discogenic pain and lumbar sprain and strain in acute low-back pain patients. Methods : Outpatients who made their first visits during May 1, 2009 to Oct. 30, 2009(n=53) were examined by history taking, physical examination, X-rays, and CT imaging. Disorders found on lumbosacral spine X-ray cuts and those on lumbosacral spine CT images were separately recorded. The relationship between treatment period, disc space narrowing and disc degeneration on X-rays, and HIVD on CT images was examined. Results : 1. Correlation between disc space narrowing on X-rays and HIVD found on CT images was analyzed. 21(72.41%) out of 29 patients having disc space narrowing on X-rays and HIVD on CT at the same level required treatment for over 8 weeks. 2. 2(50%) out of 4 Lawrence classification grade I patients, 8(66.67%) out of 12 grade II patients, and 14(70%) out of 20 grade III patients needed treatment for over 8 weeks. Conclusions : Disc space narrowing on X-ray and HIVD on CT at the same level, or disc space narrowing and disc degeneration on X-ray image alone indicate a tendency for treatment periods over 8 weeks, which is longer than the conventional treatment period for lumbar strain and sprain.