In the horticultural zone in Zapotitán, the tomato crop is affected by several diseases, but more heavily by those of fungal origin, among which stabd out the early blight (A. solani) and late blight (P. infestans). The trial was conducted at the San Andres Experiment Station, located at 450 masl average temperature of 23,8°C, a relative humidity of 36% and the soil pH of 6.3 to determine the effect of the corn plant as a living barrier. A split-plot, complete randomized block experimental design with four replications was used. Nine treatments were evaluated, divided in area of 3496 m2. were the large plts were the intercropping times and the useful area. The parameters evaluated were: severity of both pathogens and number of infested plants, tomato’s plant height, number of fruits and yield. Apartial budget analysis was conducted. The tomato crop responded favorably to the corn intercropping, lowering the incidence of A.solani and P. infestans. the corn intercropping planted 20 days before trasplanting and every three rows of tomato showed a lower severity of both pathogens, lower number of infested plants and registered the largest height of the tomato plants, which was ovrious be cause of the low severity when compared to the other treatments. The same treatment produced the largest number of fruits, yielding 22.687 kg/ha, being superior to the remaining treatments which fluctuated around 19.000 kg/ha. The analysis of the partial budget showed anet benefit, with the corn treatment 20 days before trasplanting and every three rows of tomato, of ¢ 8.500 which is higher to the benefits produced with the other treatments.