Objective: Although deep brain stimulation (DBS) is an effective treatment for movement disorders, improvement varies substantially in individuals, across clinical trials, and over time. Noninvasive biomarkers that predict the individual response to DBS could be used to optimize outcomes and drive technological innovation in neuromodulation. We sought to evaluate whether noninvasive event related potentials elicited by subthalamic DBS during surgical targeting predict the tolerability of a given stimulation site in patients with advanced Parkinson's disease. Methods: Using electroencephalography, we measured event related potentials elicited by 20 Hz DBS over a range of stimulus intensities across the spatial extent of the implanted electrode array in 11 patients. We correlated event related potential timing and morphology with the stimulus amplitude thresholds for motor side effects during postoperative programming at ≥130 Hz. Results: During surgical targeting, DBS at 20 Hz elicits large amplitude, high frequency activity (evoked HFA) with mean onset latency of 9.0 ± 0.3 msec and a mean frequency of 175.8 ± 7.8 Hz. The lowest DBS amplitude that elicits the HFA predicts thresholds for motor side effects during postoperative stimulation at ≥130 Hz (p < 0.001, ANOVA). Conclusion: Event related potentials elicited by DBS can predict clinically relevant corticospinal activation by stimulation after surgery. Noninvasive scalp physiology requires no patient interaction and could serve as a biomarker to guide targeting, postoperative programming, and emerging technologies such as directional and closed-loop stimulation.