Abstract <p>The hydraulic fracture propagation in cylindrical granite samples has been studied experimentally and numerically. Approximation of laboratory measurements by simulation results showed that the hydraulic resistance of the fracture is much greater than the hydraulic resistance of a flat channel of the same volume. So, if the fluid flow in the fracture is treated as Poiseuille flow, the model may overestimate the fracture propagation velocity even if the calculated pressure is equal to one obtained from laboratory measurements. It is shown that excess hydraulic resistance can be caused by the fracture sides roughness, and taking it into account makes it possible to obtain agreement between computational and experimental results.</p>