The capillary transport of water into granitic rocks has been interpreted on the basis of the structure of its porous network. An effective pore radius has been calculated from a three-sized single-pore model proposed by F. A. L. Dullien, El-Sayed, and V. K. Batra (J. Colloid Interface Sci. 60, 497, 1977) Considering the porous network of granites as consisting of fissures grouped in two size types, macro- and microfissures, an effective radius was found from the characteristic radii for each type and the average of these two values. Good agreement between the effective radius calculated and the radius estimated using a capillary rate value measured experimentally provides a suitable basis for identifying interrelationships between the pore structure and moisture capillary rise. In fact, it is possible to predict the process rate from only two characteristic pore sizes! corresponding to the radii of macrofissures and microfissures. The abnormally low rate of capillary rise observed in one of the granites studied could be easily interpreted as due to the involvement exclusively of the macrofissures of its porous network in capillary transport.