The assessment of iron deficiency represents a major aspect of routine laboratory chemico-clinical analysis, but the results provided by traditional hemato-clinical tests (sideremia, transferrinemia, mean cell volume and red blood cell levels) may not prove conclusive. During pregnancy iron deficiency is common and it would be extremely valuable to obtain a precise method of evaluating anemia. The assay of erythrocytic zincoprotoporphyrin (ZNPP) offers further diagnostic possibilities. This study aimed to evaluate the behaviour of ZNPP and other common laboratory indices in pregnant and non-pregnant women in order to assess the value of assaying ZNPP levels. Some common parameters for the study of sideropenic anemia were determined using the methods employed in our laboratory: mean cell volume (MCV), hemoglobin (Hb), sideremia (Fe), ferrinemia and ZNPP in women of child-bearing age. The tests were prescribed for preventive tests prior to the administration of oral contraceptives and/or in pregnant women undergoing control tests. No tests were made to ascertain professional or environmental exposure to lead or its derivatives. Precision was evaluated by calculating the coefficient of variation (CV) for repeated tests. If a detailed analysis is made of the behaviour of some parameters during pregnancy it can be seen that there is a progressive diminution of sideremia and ferritin, accompanied by increased levels of ZNPP. The potentially most characteristic parameters are ferritin and ZNPP which do not have a Gaussian distribution.(ABSTRACT TRUNCATED AT 250 WORDS)