A new microstrip phase shifter using EBG ground loaded with switching is introduced. The proposed design uses a microstrip line to achieve convenient system integration while the control voltage is applied only to the ground plane allowing a built-in RF-to-DC isolation. The EBG ground is made from a dielectric substrate covered with top and bottom metal surface that are connected together suing tightly-spaced metal vias. Periodic thin slots are placed on the top metal surface to produce an extra phase delay for the propagating microstrip mode. Our test circuit for an X-band operation introduces 4 deg/mm of extra phase delay at 8GHz from a line that is 16 degrees long when the regular ground plane is used. The simulation indicates that our circuit produced a reasonable mismatch loss from DC to 8GHz, and possesses a small dispersion with the maximum phase error of 13% at 4GHz. With a switch placed at the center of the EBG slot, two different amounts of phase delay can be selected for each EBG unit cell.