Due to a wide transparency range (0.9-17 μm), a low absorption loss (~ 0.01 cm-1), and a laser damage threshold comparable to ZGP crystals (~ 2 J/cm2), combined with excellent nonlinear, thermal and mechanical properties, quasi-phase-matched orientation-patterned gallium arsenide (OP-GaAs) crystals are well adapted for efficient mid-infrared optical parametric oscillators (OPOs). The paper discusses the best results obtained, to our knowledge, with an OP-GaAs OPO pumped by a Qswitched 2.09 μm Ho3+:YAG laser. The compact (33 × 48 cm) high-repetition rate source developed allows to achieve 4.0 W of average output power in the 3-5 μm range at 40 kHz repetition rate with a 45 % slope efficiency and a very good beam quality (M2 < 1.8). 6.4 W were obtained at 70 kHz with a 51 % slope efficiency, and 7.7 W at 100 kHz with a 46 % slope efficiency. At 40 kHz and 70 kHz, an optical damage occurred at a fluence of 1.9 J/cm2 and 1.5 J/cm2 respectively. The power is limited by the OP-GaAs crystal thickness and is expected to be scaled in thicker samples recently fabricated.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.