Haploids and doubled haploids (DHs) produced by in vitro culture of gametophytic cells, especially male gametophyto, are of great importance to plant breeding and basic science. The routine protocol of isolated microspore culture of Brassica has been established, and used worldwide. However, recently, new protocols dealing with multiple samples have been developed. Although various factors infl uencing microspore embryogenesis, plant regeneration and diplodization have been examined, attempts to enhance these effi ciencies have continued. With the advancement of molecular genetics, many approaches from both forward-and reverse-genetics for understanding the mechanism of microspore embryogenesis have been attempted. This chapter reviews the recent progress of microspore embryogenesis of Brassica in relation to culture protocol and factors affecting microspore embryogenesis, and recent achievements in elucidating the mechanism of microspore embryogenesis.