Growth and yield responses of peanuts (Arachis hypogaca L.) to preplant incorporated applications of metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] herbicide were studied at two locations in Georgia. At Sycamore, GK-7 peanuts which received 3.8 cm irrigation immediately following herbicide incorporation and planting were generally stunted and yielded less than non-irrigated peanuts. Metolachlor rates from 2.2 to 6.7 kg ai/ha reduced early and late season growth of irrigated peanuts in 1985 and 1986 but non-irrigated peanuts recovered by mid-August. Yields were suppressed only at the highest rate of metolachor in 1985, but there was no yield response in 1986 or 1987. At Tifton, emergence of Florunner peanuts was delayed and canopy height and width were reduced by metolachlor. Initial flower, peg and pod production were reduced in a linear response to metolachlor rate, resulting in differences in pod development 95 days after planting. There was a rate response for pod yield in 1985 but not in 1986 and grade did not differ either year. In general, emergence and growth were delayed and reduced by preplant incorporated metolachlor when rainfall or irrigation followed application, but yields were not reduced at labeled rates.