The Brassicaceae family includes the most important plant model Arabidopsis thaliana and many cruciferous vegetable crops. A number of close relatives of Arabidopsis and economically important Brassica species are being sequenced with whole-genome shotgun sequencing technologies. However, de novo assembly of full chromosomes is difficult, since many non-model Brassicaceae species are lacking genetic and/or physical maps. As a unique feature for Brassicaceae, the genome of each member is composed of 24 conserved chromosomal blocks, and the arrangement of the 24 blocks can be obtained from karyotype analysis via comparative chromosome painting experiments. Taking this advantage, we developed a bioinformatic tool named KGBassembler to automatically finalize assembly of full chromosomes from contigs and/or scaffolds based on available karyotypes of Brassicaceae species.