We have grown modulation‐doped AlInAs/InP heterostructures with two‐dimensional electron gases. Hall measurements and Shubnikov‐de Haas oscillations observed in these heterostructures yield electron mobilities as high as 26000, 9000, 2300 cm2/V s at 2, 77, and 300 K, with electron concentrations as high as 1.5×1012cm−2. These results demonstrate the potential of the AlInAs/InP heterostructure for power microwave applications.