The effect of three diphenylether herbicides on the control of green foxtail, kochia, velvetleaf, and ivyleaf morningglory with imazamox in soybean was evaluated in a field study conducted near Manhattan, Kansas in 1997 and 1998. Herbicide treatments were: imazamox at 26 and 44 g ai/ha; acifluorfen and fomesafen each at 140 and 280 g ai/ha; lactofen at 70 and 140 g ai/ha; and tank mixtures of imazamox at both rates with both rates of acifluorfen, fomesafen, and lactofen. Tank mixtures of 26 g/ha imazamox with either rate of acifluorfen, or fomesafen were antagonistic on kochia control, as was 44 g/ha imazamox with 280 g/ha acifluorfen 4 weeks after treatment. Tank mixtures of 26 g/ha imazamox and 280 g/ha acifluorfen or fomesafen were antagonistic on velvetleaf control. The only tank mixture that resulted in reduced ivyleaf morningglory control was 26 g/ha imazamox plus 70 g/ha lactofen. The tank mixture of 26 g/ha imazamox plus 280 g/ ha fomesafen was antagonistic for green foxtail. When a diphenylether herbicide was applied with imazamox, 44 g/ha imazamox resulted in fewer antagonistic interactions than mixtures with 26 g/ha.