We have measured erythrocyte Zinc-Protoporphyrin and serum ferritin in 125 subjects: 100 seemingly healthy controls, 17 with sideropenic anemia and 8 with erythropoietic insufficiency (sideropenia without anemia). Erythrocyte Zinc-Protoporphyrin was measured using Protofluor Z (Helena--Lab.) and serum ferritin was tested with immunoenzymatic technics. Patients with sideropenic anemia showed erythrocyte Zinc-Protoporphyrin values higher than controls, whereas serum ferritin was significantly lower than controls. Patients with erythropoietic insufficiency also showed erythrocyte Zinc-Protoporphyrin values higher than controls with statistical significance whereas the decrease of serum ferritin was not significant. Our study showed that Zinc-Protoporphyrin, in conjunction with serum ferritin, is a very useful test for evaluation of iron storage.