To the Editor. —I read an article in the DecemberArchives(1980;140:1582) concerning the use of liquid cyanocobalamin marketed for intramuscular use. According to Crosby, the injectable cyanocobalamin was used because of the unavailability of an oral form of cyanocobalamin. He claimed it would be wise "if the FDA [Food and Drug Administration] would authorize the marketing of cobalamin for oral therapy of pernicious anemia." I have written to inform Crosby that there is an oral crystalline cyanocobalamin available for use in pernicious anemia. It is marketed by the Merck Sharp & Dohme Co under the trade name Redisol (strength, 500 μg). It is marketed also by various generic manufacturers in 1,000- and 500-μg strengths; 1,000 μg daily of any of these products would probably have maintained this patient's condition in remission. If possible, I would like to know why Crosby did not use this product in this case.