We evaluated the stability of locking and nonlocking plate fixation of the pubic symphysis in a cadaveric model of an unstable pelvic injury. Five fresh cadaver pelves--intact and with an unfixed simulated Tile B injury--were tested under compressive load simulating a 2-legged stance. On each pelvis, 3 pubic symphysis fixation constructs were tested: a 4-hole unicortical locking plate, a 4-hole bicortical locking plate, and a 4-hole bicortical compression plate. There were no significant differences in displacement among the 3 fixation methods tested on Tile B pelvic simulations. Symphysis pubis fixation alone reduced the anterior superior pubic symphysis mean gap displacement by 95% and the anterior inferior pubic symphysis by 78%, compared with the noninstrumented Tile B injury. There is no evidence that anteriorly placed locking constructs confer an advantage, in terms of pubic symphysis stability, over standard anterior compression plates for Tile B injuries.