Objective The study aimed to assess measures of the clinical value of computed tomography (CT) scans in dizziness presentations at the aggregate level. Methods Using emergency department (ED) dizziness presentations captured in the National Hospital Ambulatory Medical Care Survey, the proportion of dizziness visits with a CT scan that received a central nervous system (CNS) diagnosis was measured yearly (1995-2004) and assessed for a trend over time. The independent association of having a CT scan with ED length of stay was examined using multivariable linear regression models. Results The proportion of dizziness visits with a CT scan that received a CNS diagnosis dropped 62% from 1995 to 2004 (P < .05). By 2004, 94.1% (95% confidence interval, 89.4%-96.7%) of dizziness visits with a CT did not receive a CNS diagnosis. Having a CT scan was associated with a substantial increase in the length of stay with the effect modified by the number of other tests performed (range of increase, 40-77 minutes). Conclusion The clinical value of CT scans in dizziness presentations at the aggregate level may be very low and appears to have dropped over time. Computed tomography scans in the general dizziness population could also be an important contributor to ED length of stay. Use of CT scans in dizziness presentations should be a target for efforts to optimize the effectiveness and efficiency of care.