A high-gain E-band antenna implemented with flip-chip technology is presented in the paper. The proposed antenna, which consists of an air-filled cavity and a radiating slot, is fed by a microstrip through a directly coupling solder bump structure. The air-filled cavity, which is formed by the space between two Integrated Passive Device (IPD) chips in flip-chip assembly process, can reduce loss and improve antenna gain. Simulation and measurement regarding antenna reflection coefficient, peak gain, and radiation pattern are conducted for design validation. The measured results show that the antenna can operate in E-band, and the impedance bandwidth with =S11= less than -10 dB is 10 %. The measured gains are 5 dBi at 77 GHz. The proposed antenna is well suited for the high data rate wireless point-to-point communication systems.