Unlabelled: The National Notifiable Diseases Working Group performed a ranking of 48 communicable diseases to assist with determining priorities for national surveillance. The WG offers six specific recommendations relating to the addition or deletion of communicable diseases from the list of nationally notifiable diseases., Key Recommendations: 1. Clostridium difficile-associated diarrhea, paralytic shellfish poisoning, and invasive listeriosis are recommended for addition to the Nationally Notifiable Disease List. 2. New proposals for diseases not recommended for national notification include hepatitis E, HTLV-1, and HTLV-2. 3. Dengue virus infection should be deleted from the Nationally Notifiable Disease List. (Dengue hemorrhagic fever should continue to be reported.) 4. Classic Creutzfeld-Jacob disease ranked well below the threshold for inclusion; however, it should be retained on the list because surveillance of classic CJD is key to effective surveillance of new variant disease and because consulted provinces and territories strongly favoured its retention. 5. Several diseases that ranked near the borderline for reporting should be retained on the list as follows: a. a. brucellosis, because although it does not rank highly on the basis of its endemic pattern it is a category B biological warfare agent; b. laboratory-confirmed influenza because it forms part of a functional and working surveillance approach; c group B streptococcal infection because alternative hospital-based surveillance systems do not yet capture a significant proportion fo cases. 6. Transfusion-transmitted infections were unrankable by the current system. 7. The approach to reporting dengue hemorrhagic fever, plague, West Nile virus infections, and other viral hemorrhagic fevers should be made congruent with the approach for other notifiable diseases (see Discussion). 8. The feasibility and utility of national reporting for communicable diseases that have very high incidence and low severity (e.g. chickenpox, norovirus) should be carefully considered, especially when it leads to little or no case-by-case data reported by health authorities. The WG recommends that these diseases be placed under surveillance but that case-by-case reporting not be required at the national level. Alternative approaches to tracking trends could include enumerating outbreaks in the case of norovirus or the use of sentinel surveillance, laboratory surveillance, or physician billing events in the case of varicella.