This letter presents the dc characteristics of normally Off AlInN/AlN/GaN metal--oxide--semiconductor heterostructure field-effect transistors (MOS-HFETs). The devices were fabricated using a recessed gate and SiON dielectric layers for gate isolation. For a device with a 1.5 μm gate length and an 8-μm-long channel, the threshold voltage was above +1.5 V and a maximum drain current density of 0.7 A/mm was reached under 6 V gate bias. These enhancement-mode MOS-HFETs have an excellent potential for power electronics applications.