Field trials were conducted in 2007 and 2008 early and late wet seasons, respectively at the Federal University of Agriculture Abeokuta (070 20`N, 30 23`E) in the forest-savanna transition agroecological zone of South-western Nigeria. Five weed control treatments viz pre-emergence application of commercial formulation of metolachlor plus prometryne (Codal GoldR, 412 EC) at 1.6kg a.i/ha alone, 1.6kg a.i/ha followed by supplementary hoe weeding at 6 weeks after planting (WAP), 2.4kg a.i/ha, two hoe weedings at 3 and 6 WAP and a weedy check were assigned to the main plots while intercropping methods which included four combinations of groundnuts between rows of maize spaced at 50cm and 75cm, as well as sole crops of maize and groundnut constituted the sub-plot treatments. Intercropped groundnut significantly suppressed weed infestation compared with the sole crops of maize and groundnut. Weed infestation was consistently lower in maize planted at intrarow spacing of 75cm in mixture with three groundnut stands in the inter-row between two maize stands and maize planted at 50cm in similar mixture with two groundnut stands compared with the other cropping methods. In both years of study, maximum cob and grain yields were obtained with sole maize spaced at 50cm within rows. Intercropped maize at 75cm produced grain yield comparable to the corresponding sole crop in both years. Intercropped groundnut in maize spaced at 50cm significantly reduced grain yield of maize in 2007 and non-significantly in 2008 compared to the corresponding sole crop. All the weed control methods evaluated resulted in significantly lower weed cover score than the weedy check.