Serum magnesium and calcium was examined in 70 patients with chronic dorsalgias. Values of calcium were stabilized, but values of magnesium were unstable and exceeded the 2SD lines, being more often over than under these lines. Lability of serum magnesium levels is considered a secondary consequence, caused by the stress of pain. These symptoms may be alleviated by Mg administration, by local application of Mg through transdermic iontophoresis or sonophoresis, or by hydropathy of the paravertebral muscles.