Data are presented for erythrocyte protoporphyrin (EP) concentrations determined by the direct reading tecnhique of Lamola et al. (1) Mean concentration of EP in children whose blood lead concentration was less than 30 mug/dl was 34.7 mug/dl whole blood +/- 13.4 (SD). Mean EP concentration in children with blood lead concentrations of 40-59 mug/dl was 80.0 mug/dl. It was 158 mug/dl. It was 158 mug/dl for children with blood lead concentrations greater than 59 mug/dl. All children in this last group had concordant values for Pb and EP on the first or second test.