Experiments were carried out on two Oxisol series over two seasons. In addition to sole crops of maize and beans at their recommended optimum densities, there were four intercropping systems representing all combinations of 100% or 50% of the sole crop density of each crop. Nitrogen at 0, 30, 60, 90 or 120 kg/ha was applied along the maize rows in the sole maize and the intercropping systems. The maize showed a good response to nitrogen in the sole crop and in all intercropping systems. Beans in intercropping also showed a good response as a result of the nitrogen applied to maize, an effect attributed to the poor nodulation of the crop on the acid soils. There was evidence of only slight competition from the beans on the maize at no nitrogen, but at higher levels of nitrogen the increased bean growth depressed maize yields by up to 30%. At low nitrogen levels beans were highly suppressed by the maize, but at the highest nitrogen levels bean yields approached or exceeded the yield of the sole beans. LERs were well above 1 for all intercropping systems (overall mean 1.46), indicating large yield advantages for intercropping. Contrary to most other cereal/legume studies, LERs increased with an increase in the level of nitrogen; means over the four intercropping systems were 1.27, 1.36, 1.41, 1.55 and 1.69 for the increasing levels of nitrogen. Maize being the more important crop in northern Zambia, it is reasoned that farmers are likely to assess intercropping in terms of how growing beans with maize compares with growing maize on its own. Although there was evidence of a slight decrease in maize yield due to intercropping at no nitrogen, the maize yield in intercropping with nitrogen applied was always well above the basic maize sole crop yield at no nitrogen, despite some yield loss due to competition from the beans. For any level of nitrogen used, returns to the cost of nitrogen and the overall net returns were greater from intercropping than from sole maize. It is concluded that, whatever level of nitrogen the farmer may adopt, the economics of sole maize are improved by adding a bean intercrop.