Tomatoes are one of the most important vegetable crops cultivated and consumed globally. Several wild relatives have significantly contributed to the genetic improvement of tomatoes for various traits. Genetic resources and crop diversity serve as a basic material for crop improvement. Many gene banks, globally, maintained and conserve (ex situ and in situ) tomato genetic resources which includes wild species, land races, modern cultivars, pre-bred stock introgression lines, addition, substitution lines, mutant, cytoplasmic stocks, and interspecific hybrids. Over periods, cultivated tomatoes have experienced a significant reduction in genetic diversity because of extensive selection during breeding and domestication, leading to narrow genetic variability. However, tomato wild species possess wider genetic diversity and allelic variation when compared to cultivated species. PGR are the reservoir of important traits such as biotic and abiotic tolerance, increased yield, male sterility, and quality, increasing the value and sustainability. Globally, about 63,640 germplasm of tomato crop species have been collected and maintained in over 143 regional and international ex situ gene banks. Tomato wild relatives and other genetic resources serve as valuable source of genomic information such as development of genetic maps, mapping of gene/QTL(s), functional and structural genomics, transcriptomics, cloning of genes, development of molecular markers, marker-assisted selection and gene pyramiding, which greatly facilitating accelerated tomato breeding. This chapter will discuss the genetic resources, collection methods, conservation strategies, and utilization of genetic and genomic resources for tomato improvement programs.