Field experiments in 1994 and 1995 compared control by imazameth at 53 and 71 g ai/ha and imazethapyr at 71 g ai/ha applied to purple nutsedge (Cyperus rotundus L.) 5, 10, 20, or 30 cm tall. Peanut (Arachis hypogaea L.) injury was not observed with either herbicide. Imazameth and imazethapyr were similarly effective on purple nutsedge for the first 1 to 2 mo after planting. Regardless of application timing, imazameth was more effective than imazethapyr at approximately 3 mo or more after planting. Timing of application affected late-season control by imazameth only in 1995 where greater control was obtained when applied to 10- or 20-cm purple nutsedge. Peanut yields were variable in 1994 and were not related to the imidazolinone herbicide used, the herbicide rate, or the level of purple nutsedge control. In 1995, yield from plots treated with imazameth at 53 g/ha was greater than yield from plots treated with imazameth or imazethapyr at 71 g/ha. Timing of herbicide application did not affect yield.