The back pain syndrome which accompanies involutional osteoporosis presents a marked heterogeneity. Acute pain may be due to vertebral fractures, whereas chronic pain may eventually accompany established osteoporosis in which clinical and instrumental evidence are present. Back pain is the consequence of the mechanical (internal or external pressure) or chemical stimulation of pain receptors present in bone tissue, along the vessels, in cartilage, joints, disk, ligaments, and also in soft tissue and muscle (with secondary antalgic contracture). The compression of spinal nerves may contribute to the pain as well. An evident alteration of mood is usually present and represents an important element in the syndrome. This phenomenon interferes with the evolution of pain, in particular as regards its intensity. Besides scales for the evaluation of pain and inability, it is possible to check objective data by means of particular algometers (not easy to employ) or by electromyographic measurements of antalgic secondary contracture of spinal muscle. Gait examination (basography) of patients with painful hip prosthesis may provide objective evaluation regarding specific antalgic activity on bone of drugs. Usually the effective drugs for osteoporosis possess antalgic properties as well, with different mechanisms of action. Three drugs with evident activity are taken into consideration: calcitonin, ipriflavon, aminobutane-bisphosphonate (alendronate). Though each of them possesses some particular activity, the main mechanism of action is dependent on their effect on the local microenvironment, particularly at the level of bone tissue (calcium, cytokine and prostaglandin local concentration), on the modulation of osteoclast activity. In particular alendronate (intermittently administered intravenously) exerts the most evident antalgic activity. Subjective chronic back pain relief is accompanied by (secondary) reduction of antalgic contracture at vertebral muscle level. The activity of the substance against the painful hip prosthesis (documented by basographic gait recording) leads us to conclude that the substance really exerts a direct antalgic action at the level of bone tissue.