Laser is emerging as a strong concept for alternative ignition in spark ignition engine. Laser ignition has potential advantages over conventional spark plug ignition. Laser ignition system is free from spark electrodes hence there is no loss of spark energy to the electrodes, which are also free from erosion effect. In addition, there is flexibility in choosing spark location and it offers excellent performance under high in-cylinder pressures. In this paper, performances of laser ignition and conventional spark ignition systems are comparatively evaluated in terms of in-cylinder pressure variation, combustion stability, fuel consumption, power output and exhaust emissions at similar operating conditions of the engine. (C) 2014 Elsevier Ltd. All rights reserved.