Zinc protoporphyrin (ZPP) values were analyzed with a hematofluorometer on 395 non-occupationally lead exposed subjects. Blood lead (B-Pb) determinations were concurrently carried out with an extraction procedure using flameless atomic absorption method. Applying Hoffman's Statistical Analysis with a logarithmic transformation, a normal range for ZPP (a mean of 23 microgram/dL) was established with 40 microgram ZPP/dL on the upper limit of the 95% probability range. A value of 54 microgram ZPP/dL has been found to be a suitable cutoff value above which one generally finds B-Pb values greater than 40 microgram/dL. For B-Pb values (less than 40 microgram/dL) and ZPP values in our normal range, there was essentially no correlation. However, for elevated values of both, a correlation coefficient of 0.87 was found for log ZZP versus B-Pb. ZPP values for males appeared to increase with increasing age.