Comparative ultrastructural examination and energy-dispersive electron probe X-ray microanalysis were performed on a long standing skin lesion of hemosiderotic histiocytoma. Iron-containing fine particles present in siderosome were the main element of interest. Qualitative study of spectra over the siderosomes clearly demonstrated the characteristic X-ray energy emitted by iron, whereas spectra obtained from adjacent cytoplasm revealed minimal iron peak. On quantitative evaluation of the spectra yielded from various siderosomes, iron counts intensity was found to be proportionally increased with increment in amount and electron opacity of the siderosomal inclusion. Accounts on chemical nature of the siderosomal inclusion and on the presence of lipid residue in cytoplasms were noted.