In this research work, laser cutting of 6061-T6 aluminium alloy sheets by means of a 150 W multimode pulsed Nd:YAG laser is investigated. Linear scans using the maximum average power and different cutting directions and pulse durations are executed to measure the maximum cutting speeds. Then, cutting tests are performed by varying beam travel direction, pulse duration and cutting speed. The results show that a 150W multimode pulsed Nd:YAG laser allows to cut 1 mm-thick 6061-T6 sheets with cutting speed up to 700 mm/min, obtaining narrow kerfs (< 200 μm) with a good taper angle (< 5°) and low dross height (about 40 μm)