A wideband probe-type microstrip-to-waveguide transition integrated in a low-temperature co-fired ceramic (LTCC) is presented and experimentally verified. To enhance the bandwidth, an air-hole matching structure besides the probe is buried in an LTCC substrate, which is implemented by drilling square holes on different substrate layers. The microstrip-to-waveguide transition is fabricated to verify a design with compact size. The measured results show a good agreement with simulated results.