Abstract: A two seasons experiment conducted in 1999 and 2000 planting seasons, respectively to determine the effects of maize intercropping and plant density on the incidence and severity of Cercosporo arachidicola Hori and nodulation of groundnut. Investigation revealed that groundnut intercropped with maize was highly significant on incidence and severity of Cercospora arachidicola Hori leafspot disease of groundnut at 0.05 probability level. Intercropping showed a significantly lower leaspot disease severity 0.6.4 and 0.76 and a lower nodulation of 86.4 and 87.0% in 1999 and 2000, respectively in comparison with sole groundnut 0.77 and 0.86 leafspot disease severity and 88.5 and 98% defoliation in 1999 and 2000, respectively. Plant density 250,000 plants ha-1 recorded 0.00 incidence of leafspot disease at 4 weeks of plant age in both seasons, as well as least severity of leafspot disease 0.30 and 0.35 but high nodulation of 14.75 and 13.95 in 1999 and 2000, respectively while 1,000,000 plants ha-1 had highest severity 1.15 and 1.24 but low nodulation 12.63 and 11.05 in 1999 and 2000, respectively. There is also a direct relation on severity of leafspot disease with age of groundnut planted in both seasons. Groundnut intercropped with maize had significantly high nodulation 12.44 and 13.05 when sole groundnut 11.31 and 11.55 in 1999 and 2000, respectively were low.