This study evaluated the potential of two representative soils in the Brazilian Cerrado to act as carbon sources or sinks under different tillage systems. The soils, a sandy clay loam and a clayey Oxisol, were studied under three tillage systems - conventional tillage (CT), reduced tillage (RT), and no-till (NT) - for five to eight years. The carbon stock of native, uncultivated soils provided a baseline for comparing the tillage treatments. While soil carbon under conventional tillage did not decrease significantly from the native soil levels, soil under no-till had increased carbon sequestration. Widespread adoption of no-till methods in the region could result in a contribution toward global climate change mitigation.