Objective: To evaluate the appropriateness of dopamine receptor antagonist prescriptions in hospitalized patients with dopamine-requiring diseases after implementation of an automated prescription alert system. Methods: We examined dopamine receptor antagonist prescriptions in hospitalized patients with dopamine-requiring diseases and physician response to an automated drug contraindication alert system at Barnes-Jewish Hospital from 2009 to 2013. A detailed review of patient medical records was performed for all alert events generated when a physician prescribed a dopamine receptor antagonist concurrently with a dopamine receptor agonist in hospitalized patients. Two movement disorders neurologists determined the appropriateness of each prescription, based on patient medical history, through consensus. Physician response to alert was compared by indication for the prescription and physician specialty. Results: Of 237 orders, 197 (83.1%) prescriptions for dopamine receptor antagonists were considered inappropriate. The prevalence of inappropriate dopamine receptor antagonist prescriptions per levodopa prescriptions was 16.10% (95% confidence interval 9.47, 22.73) in psychiatry, 7.51% (6.16, 8.86) in general medicine, 6.14% (4.49, 7.79) in the surgical specialties, and 0.85% (0.46, 1.25) in the neurologic/neurosurgical specialties. Of the inappropriate prescriptions, 146 (74.1%) were continued despite the alert. The strongest predictor of discontinuation of dopamine receptor antagonist medications was use of the medication to treat nausea or emesis (p < 0.001). Conclusions: Despite successfully identifying instances when dopamine antagonists were prescribed to patients with dopamine-requiring diseases, the alert system modestly affected physician prescribing behavior, highlighting the need for improved education of health care providers.