The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10 CM) will be implemented on October 1, 2013 in the United States by institutions such as hospitals and insurance companies, and by surveillance programs and registries. The Alberta Congenital Anomalies Surveillance System (ACASS) experienced a transition in 2000, changing from the British Paediatric Association version of ICD-9 (ICD-9 BPA) to the Royal College of Paediatrics and Child Health adaptation of ICD-10 (ICD-10 RCPCH). Although the United States will use ICD-10 CM, the experiences discussed are applicable to birth defects programs in the United States. ACASS is funded by the Alberta Ministry of Health known as Alberta Health and Wellness (AHW) and is primarily a passive system covering approximately 50,000 annual births in the province of Alberta. Hospitals in Alberta changed from ICD-9 to an enhanced version of ICD-10 developed by the Canadian Institute for Health Information (ICD-10 CA) in 2002. Both ICD-10 RCPCH and ICD-10 CA are comparable; however, ICD-10 RCPCH offers a more detailed breakdown of some congenital anomaly categories. Although the implementation date for ICD-10 CA was to be in 2002, Alberta hospitals were aware in 1999 that the change would occur. This 3-year period allowed for preparation by ACASS prior to the required implementation.