Economic viability of integrated weed management in maize/cassava intercrop was assessed using data obtained from research conducted in 2002 and 2004 cropping seasons in the southern Guinea savanna ecological zone of Nigeria. Costs and returns were computed from the use of Primextra (at 2.5 kg ai/ ha), a pre-emergence herbicide, legume cover crops, hoe-weeding (weeding at 3, 6 and 12 weeks after planting) and a weedy check as control, to determine the financial returns from the use of different treatment combinations. The use of Primextra alone, cover crops alone or their treatment combinations resulted in negative marginal returns for the production of the maize component of the intercrop ranging from - N400. 00 in plots treated with Primextra plus Mucuna preta to - N11, 300 in plots treated with Primextra with Mucuna jaspeada. Treatment combinations involving the use of Priemxtra plus two hoe weeding with Mucuna pruriens var. utilis gave the highest average Gross Margin per hectare (GM /ha) of N14, 850 for production of the maize component of the intercrop while Primextra plus two hoe-weeding with Pueraria phaseoloides followed the same trend for production of the cassava component of the intercrop giving N88, 000 GM/ha. These weed control treatment combinations produced considerably high marginal returns and thus can be adopted by farmers in the production of maize and cassava in an intercropping system in southern Guinea savanna ecological zone of Nigeria.