Blood donors are considered as a group with increased risk of iron deficiency. Therefore it seems particularly useful to have a simple screening test at one's disposal in blood centers to detect easily early iron deficiency. Erythrocyte protoporphyrin assay on an hematofluorometer is very easy and of a low cost. So we studied its diagnostic value on a sample of 285 blood donors (131 men and 154 women). Prevalence of iron deficiency, defined by the coexistence of, at least, two abnormal indicators (serum ferritin, transferrin saturation, erythrocyte protoporphyrin, mean corpuscular volume), was 5.6% in this sample; sensitivity of erythrocyte protoporphyrin used alone was 75% and its specificity was 91.5%. We used a decision analysis to evaluate the opportunity of screening with this test, accompanied where indicated by iron supplements. The results, though preliminary, suggest that erythrocyte protoporphyrin measurement could be of interest in screening blood donors for iron deficiency.