The authors treated 60 children with giardiasis using nitrimidazine. The patients, aged two to ten years, received 200 mg of the drug twice or three times daily, for five or seven days. The global results showed 90% of cures mid the differences between the three groups of twenty patients each were not significant. Tolerance to this antiparasitary drug was satisfatory, and this fact plus the therapeutic results obtained led to the conclusion that nitrimidazine is a new and efficient drug for the treatment of infection by Giardia lamblia.