Health evaluations of free-ranging and captive cetaceans should include WNV serology to assess exposure rates. This report focuses on killer whales, but the "loafi ng" behavior (stationary positioning at the water's surface) is commonly seen in many coastal dolphins, thereby increasing the likelihood of mosquito bites and exposure to WNV. Serologic screening of bottlenose dolphins (Tursiops truncatus) from the Indian River Lagoon demonstrated WNV titers (7) . WNV-associated disease in these animals has not been reported. Active screening for WNV may enhance diagnostic investigations.