All companies are subject to some degree of regulatory oversight of their operations. Economics, finance, and government research demonstrate that operational regulatory oversight (for example, provided by the EPA or FDA) imposes financial and operating burdens on regulated firms. My study examines how auditors respond to their clients’ operational regulatory oversight with additional audit costs, as reflected in audit fees. I focus on operational regulatory oversight from six federal regulatory agencies with authority to regulate companies in any industry. I find that operational regulatory oversight intensity, measured by number of regulators, occurrences of regulator-specific disclosures, and regulatory fragmentation, is positively associated with audit fees. Cross-sectional tests show that operational oversight from “continuous” regulators (i.e., regulators that maintain routine oversight) significantly weakens the positive association between operational regulatory oversight and audit fees. Further analyses provide no evidence that the higher audit fees are accompanied by changes in auditor effort. Lastly, my results are robust to an audit fee change model and an alternative measure of regulatory fragmentation. / Business Administration/Accounting