To evaluate the effectiveness of an electronic messaging system for accurately communicating important, but not emergent, abnormal radiology results to referring physicians. The Institutional Review Board deemed this proposal a quality improvement project that did not require formal approval. The electronic messaging system permits radiologists to submit online requests to communicate important, but not emergent, abnormal findings and recommended follow-up to two communications facilitators, who contact referring health care providers by e-mail or telephone. Of 10,510 electronic communications during a 3-year period, a representative sample of 500 communications were selected for detailed analysis. To eliminate bias associated with increased experience with the system, every 20th communication during the 3 years that the messaging system had been functional was examined. Parameters studied included the rate of successful communications with referring physicians, the frequency of these being accomplished within the goal of 48 hours from the time of radiologist submission, and the results of an e-mail survey of physicians to assess their satisfaction with the system. The radiologic abnormality was successfully communicated to the referring physician in every communication. Overall, a mean of 82.2% ± 3.3 (standard deviation) of communications were accomplished within the goal of 48 hours, with this goal being met in 93.7% ± 2.3 of communications submitted Monday through 3 pm on Thursday. Satisfaction among referring physicians was high (79.0% ± 3.8 satisfied; 5.0% ± 2.0 dissatisfied), especially among those with the most experience with the system. The electronic messaging system communicated important, but not emergent, abnormal radiology results to referring physicians in a timely, accurate, and relatively inexpensive manner. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10101015/-/DC1.