The parameters of a Q-switched longitudinally-diode-pumped Tm3+:YAlO3 laser are presented. The pulse repetition rate is f = 1–15 Hz. The maximum average output power is 5 W (at f = 5–15 kHz), the minimum pulse duration is 130 ns (f = 1 kHz), the efficiency is 26% (with the slope efficiency of 58%). The laser wavelength under pumping in the region of 803–805 nm is 1.99 μm.