Omni-band amplifiers support multiple band groups. In an exemplary design, an apparatus (e.g., a wireless device, an integrated circuit, etc.) includes at least one gain transistor and a plurality of cascode transistors for a plurality of band groups. Each band group covers a plurality of bands. The gain transistor(s) receive an input radio frequency (RF) signal. The cascode transistors are coupled to the gain transistor(s) and provide an output RF signal for one of the plurality of band groups. In an exemplary design, the gain transistor(s) include a plurality of gain transistors for the plurality of band groups. One gain transistor and one cascode transistor are enabled to amplify the input RF signal and provide the output RF signal for the selected band group. The gain transistors may be coupled to different taps of a single source degeneration inductor or to different source degeneration inductors.