Soil carbon and soil microbial biomass are closely interlinked during the process of accumulating carbon for carbon sequestration. Managed grazing on previously degraded lands has been proposed as an option for carbon sequestration in grasslands. In this context, a study was conducted from 2003 to 2005 in four grazing exclosures established more than 40 years ago and located in semiarid sagebrush grasslands of central Wyoming with the objective of evaluating the impact of long-term grazing exclusion as a grazing management practice on soil properties. Analysis of soil at two depths (0-5 cm and 5-15 cm) was done inside and outside the grazing exclosures. Soil samples were collected from under three microsites- sagebrush, grasses and bare interspaces- in each study site. Results showed differences in the studied parameters due to treatment (grazed and non-grazed), microsites and/or depths of sampling. Significant interactions among these factors were also observed. SOC in the study sites ranged from approximately 6 Mg/ha to 16 Mg/ha. Differences in SOC between grazed and ungrazed treatments were not significant. Greater MBC was observed in ungrazed soil than in grazed soil in three out of four sites signifying that MBC may have shown changes due to grazing exclusion sooner than SOC. MBC and SOC showed strong positive correlations in all study sites, with two sites showing much stronger correlation in ungrazed soil than grazed soil. These results indicate that grazing exclusion for more than 40 years may be enough to cause an increase in soil labile carbon activity and health.