The Authors treated 30 children with Giardia lamblia infection. The daily dosage employed was 400 to 600 mgm, during five days, and consequently a total posology of 2,0 gm and 3,0 gm. The cure control was made by Hoffman, Pons and Janer technique at the 8th and 25th days after treatment. The parasitological cure rate obtained was 90% (27 patients): the excellent tolerance to the drug was pointed out. The Authors concluded that Nitrimidazine is a potent, atoxic, and well tolerated drug against Giardia lamblia infection.