In this study the reference intervals for folate and vitamin B-12 were estimated according to the National Committee for Clinical Laboratory Standards Approved Guideline C28-A and International Federation of Clinical Chemistry recommendations. The study included 155 women and 124 men between ages 18-40. The health status was confirmed by history, physical examination and a questionnaire. The central 95% reference intervals of serum folate and vitamin B12 for women, determined non-parametrically, were found to be 3.9-18.1 ng/ml and 101-666.7 pg/ml, respectively: The reference values of serum folate and vitamin B12 for men were also found to be 2,5-17.6 ng/ml and 100-699.57 pg/ml, respectively. We did not observe subclass differences between females and males.