1. The effects of maleic hydrazide on growth and reproduction of the sandbur (Cenchrus tribuloides L.) under green-house conditions are reported. Tests were made with a commercial preparation, MH-40, which is the sodium salt of maleic hydrazide, equivalent to 40.0% active maleic hydrazide. 2. Solutions containing 4000 and 8000 p.p.m. of active maleic hydrazide were effective in destroying sandbur seedlings during the first 2 weeks after germination. Since a second grain in the bur may germinate subsequent to emergence of the first plant, a second and a third spray application are necessary to insure complete killing. 3. Mature plants of the sandbur were not destroyed by maleic hydrazide (4000 or 8000 p.p.m. active maleic hydrazide), although growth was retarded and fruiting was considerably reduced.