Cultivated tomato (Solanum lycopersicum) is one of the most economically important and widely grown vegetable crops worldwide. However, tomato plants are often affected by biotic and abiotic stresses that reduce yield and affect fruit quality. Phenotypic diversity is evident in cultivated tomatoes, particularly for horticultural traits, but genetic diversity is rather narrow. Major disease resistance genes for different pathogens such as viruses, fungi, bacteria and nematodes are mainly derived from wild tomato species and introgressed into cultivated tomatoes. Here, we list the major disease and insect-pest resistance genes identified in S. pimpinellifolium, S. habrochaites, S. peruvianum, S. chilense, S. pennellii, S. galapagense, S. arcanum and S. neorickii with perspective on the gap between current knowledge on tomato wild relatives and the knowledge that is needed.