Vertisols are prone to compact during agricultural work influenced, among other factors, by soil moisture. The work was carried out in areas of the Provincial Sugarcane Research Station of Holguin with the objective of determining the relationship between soil gravimetric moisture and soil resistance to penetration on a Calcic Chromic Vertisol under natural grass. Ten points were sampled, with a separation of 3 m from each other, in a 30 m transect. The soil penetration resistance was determined with a IAA/Planalsucar-Stolf impact penetrometer every 10 cm up to 30 cm depth. Soil samples were taken to determine the soil gravimetric moisture. Gravimetric moisture on the two first horizons showed highly significant differences with the existent in the layer of 20-30 cm. An inverse and exponential relationship was found between the soil gravimetric moisture and the soil resistance to penetration. Compared with the two overlying layers, in the depth of 20-30 cm, for the same value of the soil resistance to penetration there is a higher soil gravimetric moisture content, probably influenced by a greater amount of Smectite clay in the B horizon.