Oxadiazon [2-tert-butyl-4-(2, 4-dichloro-5-isopropoxyphenyl)- Δ²-1,3,4-oxadiazolin-5-one] was applied alone as a preemergence treatment and in combination with dinoseb (2-sec-butyl-4,6-dinitrophenol) as a cracking-time treatment to peanuts (Arachis hypogaea L.). During the years 1970 to 1972 the experimental area was heavily infested with a mixed population of annual grass and broadleaf weeds. During the years 1973 to 1975, the predominant species present were sicklepod (Cassia obtusifolia L.) and Florida beggarweed [Desmodium tortuosum (Sw.) D.C.]. Grass control was acceptable with 3.36 kg/ha of oxadiazon in 2 of the 3 years when benefin (N-butyl-N-ethyl-∝, ∝, ∝ -trifluoro-2, 6-dinitro-p-toluidine) was not included. Commercially acceptable control of Florida beggarweed and sicklepod occurred with application of 3.36 kg/ha of oxadiazon. Substantial control was obtained with an application of 1.68 kg/ha. Generally, the addition of 1.68 kg/ha dinoseb to oxadiazon resulted in slightly improved weed control, particularly at lower rates of oxadiazon. Oxadiazon at rates of 6.7 kg/ha or more was phytotoxic to peanuts during the early part of the growing season. This phytotoxicity generally did not result in lower peanut yields. However, treated plants were more compact.