Soils, together with forest biomass, are essential carbon reservoirs that play a key role in mitigating climate change. This study estimated soil organic carbon stock in a Regosol under a relict Pseudotsuga menziesii forest in Ejido Chinatú, Guadalupe y Calvo, Chihuahua, Mexico. Samples were collected at five depths (0-5, 5-15, 15-30, 30-60, and 60-80 cm), and organic carbon was determined using the modified Walkley and Black method. Carbon concentration decreased with depth, from 60.2 g kg⁻¹ at 0-5 cm to 24.9 g kg⁻¹ at 15-30 cm, while bulk density increased to 0.51 Mg m⁻³ at 60-80 cm. The total organic carbon stock (0-80 cm) was 100.48 Mg ha⁻¹, with the 30-60 cm layer contributing 34.21 Mg ha⁻¹. These findings highlight the importance of considering the entire soil profile when developing conservation and sustainable management strategies for temperate forests.