BACKGROUND: Central cancer registries collect tumor-related data to monitor incidence rates and support population- based research. One concern with using registry data for research is timeliness of reporting. Timeliness has been recognized as an important data characteristic by both the Centers for Disease Control and Prevention and the National Academy of Medicine. Yet, few studies in the United States have systematically measured timeliness. The purpose of this study is to evaluate timeliness in cancer-case reporting to a state population-based cancer registry. METHOD: Using the Indiana State Department of Health Cancer Registry, 66,395 breast, colorectal, and lung cancer diagnoses recorded during the years 2001–2009 were examined for timeliness. Timeliness was measured from the date the cancer was diagnosed to when the data were available at the state registry. Differences over time and among the 3 cancer types were examined. RESULT: Timeliness of reporting improved since 2003. Mean reporting time ranged from 426 days in 2003 to 253 days in 2009. We found significant difference in reporting time between the 3 cancer types. CONCLUSION: Timeliness of reporting has improved over time. Advances in health information technologies may have contributed to this improvement. However, achieving even more timely reporting for research purposes and care intervention may require moving away from traditional reporting methods.