In the United States, millions of hectares of highly erodible cropland have been in the Conservation Reserve Programme (CRP) for the past 10 to 20 years. Any conversion of CRP land back to maize (Zea mays L.) and soybean (Glycine max L. Merr.) production would require the use of conservation tillage systems such as conservation tillage to meet federal and state soil erosion control standards. Evaluations of crop yield response of these conservation tillage systems such as no-till (NT) and chisel-plow (CP) over time are needed to assess the return of this land to crop production. A 14-year study was conducted in southern Illinois on land similar to that being removed from CRP to evaluate the effects of conservation tillage systems on maize and soybean yields and for the maintenance and restoration of soil productivity of previously eroded soils. In 1989, NT, CP and moldboard plow (MP) treatments were replicated six times in a Latin Square Design on sloping, moderately well drained, moderately eroded soil. The 7-year average maize yields were similar (9.53, 9.26 and 9.46 Mg ha-1) for NT, CP and MP systems, respectively, as a result of a significantly higher yield with the MP system in the first year which offset the higher yields with the NT and the CP systems during the last six years of maize. The 7-year average soybean yield with NT (2.57 Mg ha-1) was 7% higher than with MP (2.38 Mg ha-1) and CP (2.38 Mg ha-1) systems. Crop yields for 14 years (7 years maize and 7 years soybean) appear to show improved long-term productivity of NT compared with that of MP and CP systems.