Growers in the Pacific Northwest remain interested in utilizing mustard (Sinapis alba L.) in crop rotation. The objective of this research is to determine benefits and detriments of incorporating mustard into direct seed cereal rotations. The two treatments, mustard and barley (Hordeum vulgare L.) were direct seeded in 2002-2004 on fields with at least 4 years of continuous cereal grains. Treatment crop yields and economic data were collected. Relevant subsequent cereal crop data in 2003, 2004 was collected and 2005 is being collected. The trial is a randomized complete block design with 4 replications, and the farm averages 310 mm/year of precipitation. Plots are 0.5 ha in size and the grower seeds, maintains, and harvests them. Barley had higher yields each year, averaging 1,462 kg/ha compared to 577 kg/ha for mustard, but yields varied and were below average in 2002 and 2004 and above average in 2003. Following 2002, there was no difference in subsequent grain yield and 2-year combined economic performance. In 2003 when yields were above averages mustard had significantly greater returns at $412/ha compared to $237/ha for barley, however subsequent grain yields were different. There was 46 mm less soil moisture to a depth of 1.5 M following mustard, resulting in a 26% decrease in yield. However, despite lower yields the two-year combined economic return was $89/ha greater following mustard. In the spring prior to herbicide application and seeding subsequent cereal crop, there was less weeds following mustard two out of the three years and averaged 82% less weeds overall in comparison to following barley. Overall mustard has an opportunity to be used in cereal grain rotations in the PNW especially in comparison to barley. It produced returns equal to or greater than barley and was able to offset reduced subsequent crop yields following 2002.