Molecular markers, such as PCR-based and SNP-based markers, are extremely useful for plant genetics and crop breeding. Marker-assisted selection (MAS) has been widely applied in plant breeding to improve crop yield, quality, and tolerance to biotic and abiotic stresses. To develop gene-based (or -specific) molecular markers, three different approaches have been used in Brassica species: Known-gene-based, RNA seq/Exon-based and RNA seq/Intron-based molecular marker development for several years. Using these techniques, molecular markers have been developed to identify flowering time, anthocyanin accumuation and abiotic stresses in B. rapa and B. oleracea. Markers were distributed in exons as well as introns, and coding sequences and untranslated regions (UTRs). All markers developed have been transformed into SNP marker after HRM confirmation. I will discuss efficiency, accuracy, and potential problems and contribution of these markers for Brassica breeding.