D. N. P. 2, 6-diiodo-4-nitrophenol, a new agent in veterinary medicine against ancylostoma caninum and ancylostoma braziliense, under the name of disofenol was prescribed in single oral doses of 1, 2, 3 and 4 mg. per kilogram of human body weight, in order to evaluate its effectiveness against ancylostoma duodenale and particularly, its absorption, blood concentration and elimination in highly parasitic subjects. Is was given to 16 subjets, divided into separate groups, and administered by increasing amounts of doses. No activity at all was observed against ancylostoma duodenale by this compound on evaluating its action by counting the number of eggs passed with the feces by stoll's method. No toxic reactions or secondary side effects were observed with the doses given.