Chinese cabbage (Brassica rapa ssp. pekinensis) is one of the most important vegetables and widely cultivated in Asia countries including Korea and China. Recently, whole genome sequence and full-length cDNA information of this species became available, which are encouraging genetic studies of this species to characterize agricultural important traits. Orange-colored (Or) cultivar of Chinese cabbage has inner leaves in orange, whereas other cultivars generally cultivated have yellow (Ye)- or white-colored inner leaves. In this study, we investigated phenotypes and carotenoid biosynthesis genes related to color variation in the Or cultivar. Firstly we compared the carotenoid content and composition between the Or and Ye cultivars by HPLC analysis. The inner leaves of Or cultivar contained approximately 9-fold high β-carotene content, whereas content of both lutein and violaxanthin was decreased to less than 30%, compared to Ye cultivar. Or cultivar was segregated with ratio of 3:1 in F2 population derived from crossing between Or and Ye inbred lines, indicating that Or phenotype is controlled by single recessive gene. To identify this gene, we investigated the expression of several genes involved in carotenoid biosynthesis by RT-PCR analysis. Among genes tested, two encoding putative carotenoid isomerase (CRTISO) and phytoene desaturase (PDS) were identified to show different expression between Or and Ye cultivars. Through further analysis of genomic DNA regions of these two genes, we could expect that several mutations such as InDel and base-substitution occurred and then affected expression of these genes in Or cultivar. In this presentation, I will introduce more detailed results for Or cultivars.