To the Editor: The recent article by Halsted and his colleagues describes the mechanisms of sulfasalazine-induced folate malabsorption and reports low serum folate levels in four of five patients given the drug, as compared with normal levels in 10 nonusers (December 17 issue).1 We are concluding a hematologic study that included measurement of folic acid in 45 patients with chronic colitis, 27 of whom had taken sulfasalazine for at least three months. No patient was taking supplemental folic acid. There was no significant difference (P = 0.32 by t-test) in serum folate levels between those taking sulfasalazine and those not. © 1982, Massachusetts Medical Society. All rights reserved.