Greenhouse experiments were conducted in 2008, 2009 and 2010 growing seasons to determine the incidence of symptomatic and asymptomatic infection by Cephalosporium maydis the causal agent of late wilt disease of maize. The percentage of healthy appearing plants that incubating the fungus (asymptomatic) ranged from 5 to 68% whereas visually infected plants (symptomatic) was in between 0 to 100%. There was no positive correlation between the degree of resistance and asymptomatic infection. Based on the occurrence of asymptomatic infection by C. maydis, under inoculum of single isolate, mixture isolates and different levels of its density, on resistant or susceptible genotypes it is concluded that asymptomatic of late wilt disease is evident and maize plants used tolerance as a defense against the causal agent of late wilt disease.