Since July 26, CDC and Health Canada, in cooperation with local public health authorities, have been investigating reports of febrile respiratory illness and associated pneumonia among persons traveling on land and sea, both independently and on tour packages, in Alaska and the Yukon Territory. Commonly reported symptoms include fever and cough, and laboratory evidence suggests that influenza A infection may be a cause of many of the illnesses. Summertime outbreaks of influenza A have previously been reported among tourists in the United States and Canada. No evidence suggests increased respiratory illness activity among residents of these areas.