Field trials were conducted on the farm of the Institute for Agricultural Research, Samaru, Nigeria, during the 1985 and 1986 rainy seasons (May‐October) to evaluate herbicide treatments for weed control in the Simultaneous system of farming with sorghum—groundnut mixtures. Most of the low rates of herbicide treatments followed by supplementary hoe‐weeding (SHW) reduced weed infestation better than the higher rates without hoe‐weeding, but comparably to the twice hoe‐weeded control. Propachlor plus terbutryne at 2.0 + 1.0 kg a.i./ha, followed by SHW, was found to be promising in terms of selectivity in the component crops, with season‐long weed control, and to improve both sorghum and groundnut yield, which are comparable to the hoe‐weeded control. Pree (Metazachlor with ‘antidote') plus terbutryne at 0.5 + 1.0 and 0.75 + 1.0 kg a.i./ha, with and without SHW, respectively, although effectively reducing weed infestation and improving groundnut yield in 1985, produced high pod yield in 1986 only in plots treated with the low rate followed by SHW; moreover it was found to be phytotoxic to sorghum establishment and growth, which resulted in reduced grain yield. In these trials SHW was therefore found to be very important for an effective season‐long weed control.