Brown condiment mustard (Common Brown) has about 10% lower grain yield than oriental condiment mustard (yellow seeded), which both belong to the same species [Brassica juncea (L.) Czern.]. Yield improvements in brown condiment mustard are therefore of great importance. The Saskatoon Research Centre of AAFC initiated a condiment brown mustard improvement program in 1996 applying pedigree selection of single plants from the condiment brown mustard cultivar Blaze, which resulted in the selection and registration of the cultivar Centennial Brown. Centennial Brown yielded 3.2% more grain than the landrace Common Brown, on average over 81 location years in 9 yr of condiment mustard Co-op tests (1999–2007) and was well adapted to the mustard-growing areas of the Canadian prairies. Support for registration was based on 6 yr of Co-op tests. Centennial Brown had the same maturity (91 d) and was 5 cm taller (116 cm) than Common Brown. It had 1.5% lower fixed oil (36.6%) and 1.2% greater protein content (30.0%) compared with Common Brown. It had 0.4 g heavier seed (2.96 g 1000 seed-1) than Common Brown. Centennial Brown had 0.9 mg g seed-1 greater allyl glucosinolate content than Common Brown (9.15 mg g seed-1). Green seed counts were low in Centennial Brown (0.64%) compared with Common Brown (0.79%). This was confirmed in chlorophyll content measurements, 4.76 mg kg-1 for Centennial Brown and 5.24 mg kg-1 for Common Brown. Centennial Brown was resistant to blackleg disease [Leptosphaeria maculans (Desm.) Ces. et de Not.] and highly susceptible to the B. juncea races of white rust [Albugo candida (Pers.) Kuntze], equal to Common Brown. Centennial Brown will quickly replace Common Brown in the market place because of its increased grain yield and much superior seed quality. Key words: Brassica juncea (L.) Czern., cultivar description, grain yield, seed quality