Intercropping of maize and cowpea is widely used by Brazilian family farmers. The aim of this work is to compare the grain yield of two maize cultivars, and one cultivar of cowpea in organic system. Treatments of monoculture of cowpea (Poços de Caldas) and maize ('BR106' and 'AG1051') and intercropping were used. A randomized block design with four replicates in an area under conversion to organic production system was used. The experiment was conducted in the period of October 2012 to March 2013, corresponding to the periods of spring/summer. The maize alone was on average, 26.5 cm taller and grain yield was 28% higher than in the intercropping. The cowpea intercropped with maize 'AG 1051' was 3.8 cm taller than the intercropped with 'BR 106'. In monoculture, the cowpea presented more (0.7 and 1.2 grain per pod when intercropped with 'AG 1051' and 'BR 106', respectively). The cowpea monoculture resulted in 2.4 pods per plant than in intercropping and productivity was 5.4 times higher than that of the intercropping. The cowpea intercropped with 'BR 106' was efficient, while that with 'AG1051' was inefficient in terms of land equivalent coefficient.