Abstract: Collisional effects on the kinetics of interactions between an ultrahigh intensity subpicosecond laser and a solid carbon thin foil are investigated in the scenarios of laser-driven particle acceleration and fast ignition by one-dimensional particle-in-cell simulations. It is found that collisional effects play an essential role in hot electron generation and transport in the early transient time by slowing down the return current which supplies resistive heating, compared with collisionless cases. Qualitatively, collisional effects reduce hot electron production and its maximum energy, and suppress energy transport. However, when recirculation (or refluxing) processes become the major transport mechanism in later time, the two cases have less difference.