Objective: This study was conducted to automatically improve the completeness and validity of the Daegu Cancer Registry, using cross record linkage of many data sources, and to develop a computerized patient enrollment system for efficient communication among cancer researchers via the internet. Method: We analyzed 10,229 cancer patients who were reported in the National Cancer Registry, and from pathological reports, health insurance cancer claims lists, cancer patient records at hospital information centers and death certificates from the Korea National Statistical Office. Result: We confirmed 4,624 cancer patients and found 897 of new cases from a review of medical chart. The new cases were detected efficiently using cross record linkage. We developed a computerized patient enrollment system, based on a client-sewer model, for the input of cancer patients, and then developed a web-based reporting homepage and patient enrollment system for the internet. Conclusion: This system could manage cancer databases systematically, and could be given to other researchers as a basic database.