From October 3 through April 28, moderate to severe influenza outbreaks were reported in the Americas, Asia, and Europe. Influenza A (H3N2) viruses were associated with outbreaks in Africa (Tunisia), Asia (China, Hong Kong Special Administrative Region [SAR] of China, Iran, and Japan), Europe (Albania, Austria, Belarus, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Finland, France, Germany, Hungary, Iceland, Ireland, Israel, Italy, Latvia, Netherlands, Norway, Poland, Portugal, Romania, Russian Federation, Slovakia, Spain, Sweden, Switzerland, Ukraine, and United Kingdom), and North America (United States and Canada). Influenza A (H3N2) isolates from sporadic cases were reported from Argentina, Australia, Brazil, Republic of Cyprus, Egypt, Greece, Guam, French Guyana, India, Republic of Korea, Malaysia, Mauritius, Mexico, New Zealand, Peru, Philippines, Senegal, Singapore, South Africa, Syria, Taiwan, Thailand, Turkey, and the Federal Republic of Yugoslavia. Of the A (H3N2) isolates that were characterized antigenically, most were similar to the reference strains A/Moscow/10/992 and A/Panama/2007/99 viruses. Many isolates also were closely related to the A/Sydney/05/97-like (H3N2) virus.