Our objectives were to determine the likelihood of true folate deficiency among patients tested for this disorder, to identify whether there were differences between the clinical indications for folate testing in folate-normal and folate-deficient patients and to assess the impact of a diagnosis of folate deficiency on patient management. The results of all blood samples analyzed for serum and erythrocyte folate levels during the year 2001 at the Cleveland Clinic Foundation were retrieved. Folate deficient patients were identified and their medical charts were reviewed to determine the indications, patient characteristics, and impact of this diagnosis on patient management. For comparison, medical chart review was also conducted on a control group composed of an equal number of randomly selected patients with normal serum folate values. A total of 6024 (4689 serum and 1335 erythrocyte) samples from 4985 patients were collected. In the study, 77 (1.6%) of the serum folate levels, from 74 patients, were identified as low. When compared with the control group, patients with low serum folate levels had lower hemoglobin and a greater red cell distribution width. Mean corpuscular volume, however, did not differ between the two groups. No significant differences in the clinical indications for serum folate level determinations could be identified. Only 39 of the 74 patients with low serum folate levels were given folate replacement, representing only 0.9% of the clinically suspected and tested patients. We conclude that determination of serum folate level infrequently led to appropriate folate replacement therapy. Moreover, even when suspected, true folic acid deficiency is rare and clinical indications are not helpful in diagnosis.