The content of soil organic matter (SOM) with regards to soil structure was evaluated in Chernozems of the Danube Lowland (Slovakia). The content of water-stable macro-aggregates (WSA_ma) in the studied soils was on average 74.6%. Important from the agronomical viewpoint aggregates fraction 0.5–3.0 mm amounted on average 29.9%. The average content of soil organic carbon (SOC) was 13.5 ± 3.78 g kg^-1 and it was significantly higher as compared to the content of this element in water-stable micro-aggregates (WSA_mi) (10.5 ± 4.22 g kg^-1). The highest content of SOC was in the WSA_ma (13.8 ± 4.36 g kg^-1). The content of labile carbon (C_L) was on average of 2.03 g kg^-1. On average, the contents of C_L in water-stable aggregates (WSA) were lower as compared to C_L in soil. SOC decreased with rising sand content. In contrast, SOC increased with increasing clay and silt contents in the soil. The content of SOC in WSA was conditioned by SOC concentration, the content of silt and clay fractions as well as by the content of WSA. The same trend was observed for C_L in WSA; however, C_L in WSA_mi was not affected by C_L in soil, rather by SOC with combination of other parameters such as: silt and clay contents and content of WSA_mi.