We tested an electronic cause-of-death query system at a hospital in New York City to evaluate clinicians’ reporting of cause of death. We used the system to query clinicians about all deaths assigned International Classification of Disease code J189 (pneumonia, unspecified) as the underlying cause of death. Of 29 death certificates that generated queries, 28 were updated with additional information, which led to revisions in the underlying cause of 27 deaths. The electronic system for querying reported cause of death was feasible and enabled quicker than usual responses; however, follow-up with clinicians to ensure timely, accurate, and complete responses was labor-intensive. Educating clinicians and enforcing reporting standards would reduce the time and effort required to ensure accurate and timely cause-of-death reporting.