AAC Brown 18 is the first brown mustard [Brassica juncea (L.) Czern.] hybrid variety developed using an improved Ogura cytoplasmic male sterility hybrid system at Agriculture and Agri-Food Canada — Saskatoon Research and Development Centre (AAFC-SRDC). AAC Brown 18 has significantly higher (24%) yield than the check variety Centennial Brown. It is resistant to white rust race 2a, whereas Centennial Brown is susceptible to race 2a. AAC Brown 18 is well adapted to all mustard growing areas of western Canada.