Ferritin, an iron-containing protein widely diffused in nature, has the important biochemical function of being the principal reserve and regulator for Fe3+ levels in blood and tissue. Due to its natural, effectively non-toxic iron content, ferritin has been the object of strong interest in the development of pharmaceutical products for use in iron deficiency treatment. Therefore, the need has arisen for the analytical characterization of this industrial product, be it in the hydroglyceric solution or dry powder form. The main considerations for the characterization of industrial ferritin are the following: a) iron content in both the unmodified product and the precipitated protein; b) protein content and protein/iron ratio; c) protein identification by means of polyacrylamide gel electrophoresis (PAGE); d) confirmation of protein identity and evaluation of molecular weight by means of size exclusion chromatography; e) identification and evaluation of other components of bulk ferritin preparations such as preservatives, excipients for lyophilization, water and concomitant proteins. Eight different samples were examined using the above considerations. Among the qualitative and quantitative results reported, of particular interest are those obtained by means of size-exclusion high performance liquid chromatography (SEC-HPLC). With a UV "diode array" detector it is possible to discern the peaks for ferritin and its molecular aggregates from those of concomitant proteins and preservatives; furthermore, it is possible to evaluate their molecular dimensions. Using this method, the ferritin monomer and other protein fractions can be quantitatively analyzed either by calculating area percent distribution of the chromatographic peaks or by comparing the sample with a highly pure external standard of ferritin.