The objective of this study was to evaluate the long-term effects of tillage systems, N fertilization and crop rotation on the distribution of C and N in soil aggregate-size fractions. Soil samples were taken from 0-5 cm at four locations in Kansas with different years under tillage systems: Tribune (16 yr), Hays (37 yr), Ashland (29 yr), and Parsons (20 yr). Tillage treatments were: conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Crop rotations evaluated at Ashland were: sorghum/sorghum, soybean/sorghum, soybean/soybean, wheat/soybean and wheat/wheat. Soil samples were separated into four aggregate-size classes (>2000 or >1000, 250-2000 or 250-1000, 53-250, and 20-53 µm) by wet sieving. Carbon and N were determined in each aggregate-size class. Overall, no-till systems tended to have greater aggregate-associated C and N in the fraction > 2000 µm. At the Hays site N application significantly increased aggregate-associated C and N in the >2000 µm and 250-2000 µm fractions. At Ashland site, wheat/wheat and sorghum/sorghum rotation had the greatest aggregate-associated C at the fraction >1000 µm under NT systems. The increased in soil C related with management is reflected by the increased in C associated with macroaggregates.