Such analysis permits estimation of the time elapsed since the last treatment by permanent-wave and even earlier treatments. Energy dispersive X-ray microanalysis was conducted in a Jeol JSM-35 scanning electron microscope equipped with a PGT-1000 X-ray microanalyzer. The accelerating voltage used was 25 kV. The tilting angle was 45 degrees. Hair samples were pulled from members of the laboratory staff and were not washed or otherwise cleaned. Nontreated hairs of 15 persons were examined. In three cases, only the Ca content was very low in the tips. For several of the remaining hair tips investigated, the calcium content was comparable to that of once-treated hair. The type of information now obtainable from Ca analyses of human head hairs and potentially valuable for forensic comparison of hair includes the time elapsed since the latest hair treatment and previous hair treatments, the concentration of Ca in treated hairs at a certain distance from the hair root, and the slope of the lines for the dependence of Ca content on the distance from the root for nontreated hairs. Graphic data and 12 references are provided.