Summary:Field trials were conducted to evaluate herbicides for weed control in groundnut from 1977 to 1979. The pre‐emergence herbicides used were alachlor and metolachlor, applied alone or mixed with terbutryne. Some treatments were followed either by post‐emergence bentazone or by one supplementary hoe‐weeding. In the southern Guinea savanna zone, where early grass weed control was more important, alachlor or metolachlor at 1.5 kg ha−1gave adequate weed control and pod yields comparable with that of the hoe‐weeded check. There was no advantage in adding terbutryne, or in supplementary hoeweeding or post‐emergence bentazone application. In the northern Guinea savanna zone, grass and broad‐leaved weeds were equally important. Application of alachlor, metolachlor or mixtures with terbutryne (2:1) at 1.5 kg ha−1required post‐emergence application of bentazone or supplementary hoe‐weeding for effective weed control and high pod yield. The reduction in pod yield on untreated control plots ranged between 18 and 70% of the best treatm