Apple (Malus domestica Borkh.), an important horticultural crop, produces human health-promoting metabolites during fruit ripening. Because that process, which involves complex biochemical and physiological changes, is genetically programmed, molecular and genetic approaches have been taken to understand the associated cellular mechanisms. The release of 151,687 apple expressed sequence tags (ESTs) into a public database has made possible large-scale studies of expression. Analysis of apple ESTs allows far the identification and characterization of genes with potential roles in fruit development, particularly those related to aroma production and protein degradation during ripening. Apple cDNA and oligonucleotide microarrays have been generated far more comprehensive examinations. Such tools are powerful means for elucidating the molecular events involved in metabolite biosynthesis and physiological changes and will also enable researchers to understand how to control that ripening process.