In this paper, a Q-band balanced low noise amplifier (LNA) for radio astronomy applications is presented using 0.15-μm InGaAs metamorphic high electron mobility transistor (MHEMT) process. By using the balanced configuration, the input/output return losses and output 1-dB compression point of the LNA are improved. For the on-wafer measurement, the balanced LNA exhibits a broad bandwidth of from 27.3 to 50.7 GHz with a small-signal gain of 23.1 dB. The balanced LNA is further assembled in a packaged module for the cryogenic measurement. At a cryogenic temperature of 28 K, the average small-signal gain is higher than 19.5 dB from 30 to 50 GHz with the minimum equivalent noise temperature of 44.8 K. The proposed balanced LNA exhibits potential for radio astronomy applications due to its high small-signal gain, low noise, and low dc power consumption.