the paper presents recent progress in the investigation of variability and genetic resistance in relation to rust and red stripe diseases of sugar cane in argentina. experimental results for rust innoculation under controlled conditions served to postulate that both basal peroxidase activity and its rate of increase after innoculation with the disease could be complementary mechanisms in the expression of resistance in different cultivars. molecular diversity of rust populations collected in the field in north west argentina were also investigated based on 538 aflp markers. samples collected in different varieties and sites indicated that rust uredospores populations correspond with a single mixed undifferentiated population with a high degree of intrinsic genetic variability. in regard to red stripe it was possible to optimize an effective procedure for the isolation, identification and genetic characterization of the disease agent. results permitted for the frst time the identification of acidovorax avenae as the agent responsible for the disease in argentina. the profile analysis for rep-pc and rapd indicated the presence of at least four different biotypes of the disease in salta and tucumán. the occurrence of genetic diversity among isolates permits the design of strategies for the control of the disease by means of resistant varieties.