Ultrasonic dispersion of extensional waves in fluid‐saturated porous cylinders is studied by analyzing generalized Pochhammer equations derived using Biot’s theory. Cases with open‐pore surface and closed‐pore surface boundary conditions are considered. For both cases, the dispersion of the fast extensional wave does not differ much qualitatively from the dispersion expected for extensional waves in isotropic elastic cylinders. A slow extensional wave propagates in the case with a closed‐pore surface but not in the case with an open‐pore surface. The propagating slow wave has very weak dispersion and its speed is always lower than, but close to, the bulk slow wave speed.