Mechanisms involved in fruit size/growth are diffic ult to unravel because of complex interactions between cell specification, polarity, asymmetric division, rearrangement and growth. In the recent years, genomic approaches inc luding transcriptome, proteome and metabolome analyses have produced a wealth of candi date genes possibly involved in the control of biological processes or traits of intere st, such as fruit size. Following their discovery, the relationships between the candidate genes identified and the processes or traits of interest must be confirmed, and gene func tion needs to be assed. Forward genetics appears as the most powerful approach for the ident ification of new gene functions and mutant collections offer invaluable resources for d iscovering new phenotypes and new allelic variants. Thanks to the recent availability of tomato genomic sequence and the current availability of deep sequencing tools, link ing genotypic variations to associated phenotypic changes is now more accessible. We gener ated highly-mutagenized tomato EMS mutant resources using the miniature tomato cultiva r Micro-Tom for genetics approaches in tomato. This collection has been used, in part, for identifying novel fruit size mutants in tomato and, last, give some hints on how current de ep sequencing technologies may be used for identifying unknown mutations responsible for phenotypic changes in Micro-Tom mutants. Towards this end, a Micro-Tom EMS mutant c ollection of 3500 phenotyped lines available at INRA Bordeaux was screened for fruit s ize (small or large fruit) and pericarp thickness (thick or thin) mutants. Among these, 36 mutant lines were selected (21 fruit size mutants, 15 pericarp thickness mutants). Following confirmation of the phenotype, 20 mutant lines were submitted to detailed fruit devel opmental analysis in view of identifying fruit growth processes altered in these mutants. Th e results illustrate how screening mutant collections, which is relatively straightforward on ce the initial characterization of the mutant collection and the construction of the database hav e been done, can successfully contribute to the isolation of a large number of new fruit siz e/growth mutants and thus provide new genetic material for deciphering the mechanisms inv olved in the control of fruit growth and size.