late blight caused by the oomycete phytophthora infestans is a destructive disease of tomato in brazil and other tropical and subtropical regions. the purpose of the present study was to analyses the inheritance of resistance to late blight and determine the genetic factors contributing to the resistance in the inbred line in '163a'. the line '163a' resulted from interspecific cross between solanum lycopersicum and s. habrochaites f. glabratum. inoculated field with mixture isolates of pathogen with 1000 spores ml-1 and naturally infested field trials showed that the expression of '163a' against multiple isolates of the pathogen was stable. the genetic analysis supported the hypothesis of two recessive genes controlling the resistance. the scaling test of additive-dominance model showed that is a good fit for the data confirming the absence or neglect of epistasis.