Pain in one leg and no pain in the other leg is common in the following cases: 1. Most commonly because of lumbar disc herniation compressing nerve roots, resulting in radiating pain in one lower extremity, pain characterized by stabbing pain, involvement pain, discharge-like pain. The pain is characterized by stabbing pain, involvement pain and discharge-like pain. Because lumbar disc herniation is common for lumbar four lumbar five, lumbar five sacral one disc herniation, so the painful lower limb area is generally concentrated in the back of the thigh, the back of the calf or lateral, the back of the foot or the sole of the foot, the dorsal side of the big toe, such pain is generally more intense, need to take oral non-steroidal anti-inflammatory painkillers, with dehydration, anti-inflammatory drugs to relieve pain. 2, because of unilateral lower limbs appear deep vein thrombosis The pain is generally intermittent, which is aggravated after walking and can be relieved after rest.