Two three-year field studies were initiated near Thief River Falls, MN in 2003 (03CRye) and 2004 (04CRye) to better understand the effect of crop rotation and a rye cover crop on growth and development of canola and wheat. In the second year of the studies, canola yields were reduced (15.5 in 03CRye and 10.7% in 04CRye) and seed protein content was increased (6.6 and 9.5%) but test weight was not influenced when rye was grown as a cover crop. Canola mid-season plant biomass and plant height at harvest were reduced when rye was grown in 03CRye, but was not influenced by the rye in 04CRye. Canola test weight, plant height, seed protein content, and sclerotinia disease incidence and severity were not influenced by whether the previous year’s crop was wheat or canola. Canola yield was reduced 9.0% in 04CRye when following canola compared to following wheat. Canola yield was not affected by previous crop in 03CRye. Wheat yields were reduced (9.2 and 19.1%) when rye was grown as a cover crop compared with no rye, as were test weights (0.5 and 1.6%), mid-season biomass (29.0 and 66.4%), and plant heights at harvest (4.5 and 8.9%). In 04CRye, wheat protein content and 1000 kernel weight were decreased (8.1 and 10.5%) when rye was grown, but this did not occur in 03CRye.Wheat yields were reduced (9.2 and 19.1%) when rye was grown as a cover crop compared with no rye, as were wheat test weights (0.5 and 1.6%), mid-season biomass (29.0 and 66.4%), and plant heights at harvest (4.5 and 8.9%). In 04CRye, wheat protein content and 1000 kernel weight were decreased (8.1 and 10.5%) when rye was grown, but this did not occur in 03CRye. These results document the negative influence of a rye cover crop preceding canola and wheat.