<span name="style_bold">Objective: </span>To compare two technologies sharing the same principle to determine serum folates in women of childbearing age; and to show the technological improvements, as well as the validity of the derived results. Method: The size of the sample was calculated using the procedure proposed by Fleiss (1981), a multi-stage sampling design was applied and an adjustment due to experimental design of 1,5 was included in the statistical analysis. <span name="style_bold">Results: </span>From the laboratory perspective an improvement in the analytical variability of the folate determination is observed, expressed as the percentage of inter-assay variation coefficient, carried out with two different analytical systems where the variability was 15,3 % with Radio Inmuno Essay and 6,4 % with the automated chemi-luminescent method. The concentration of folates showed a progressive increase during the studied period. <span name="style_bold">Discussion: </span>Historic evidence of 13 years of study demonstrates the technological progress and the improvement in the folate concentration in the population, as a result of the fortification of food that was implemented in Costa Rica from 1997 onwards, including mainly wheat and cornmeal flours rice, and milk.Historic evidence of 13 years of study demonstrates the technological progress and the improvement in the folate concentration in the population, as a result of the fortification of food that was implemented in Costa Rica from 1997 onwards, including mainly wheat and cornmeal flours rice, and milk.

radio-isotope techniques; Immunoassay; Chemistry Techniques; Analytical; Quality Control