Introduction. This study examined movements of the center of pressure (CoP) during forward gait initiation, in Parkinson disease (PD) patients and healthy controls, in a dual task paradigm with manipulations of cue expectancy. Methods. The CoP trajectory was divided into three periods and, prior to testing, subjects were given instructions as to whether they would receive the cue to initiate gait. The secondary task was a numerical recitation. Results. PD patients demonstrated significantly reduced CoP movements and greater variability in the timing of the vocalizations compared to healthy controls. Both groups demonstrated significant increases in CoP movements when uncertain and significant increases in counting cadence when dual tasking. Conclusions. PD patients constrained their CoP movements more than healthy controls, reflecting a need to control stability, and uncertainty in task timing cues reflected increases in CoP movements during gait initiation in both PD patients and healthy controls.