We have performed a theoretical study on the atomic geometry, electronic structure, and scanning tunneling microscopy (STM) images of the InP(111)A-(2x2) surface by using ab-initio pseudopotential calculations. We found that the most favorable reconstruction is an In-vacancy buckling structure, characterized by a complete transfer of electrons from the In dangling bonds of the outermost in atoms into the P dangling bonds adjacent to the In vacancy sites. The STM images of the simulated empty- state conclusively show that bright protrusions arise from a regular array of the surface In (the surface P) atoms; this is in good agreement with the experimental observations.