Robert Ernst, a 59-year-old marathon runner and Wal-Mart worker who was taking the arthritis painkiller at the time of his death.
Ernst died of a heart attack and the verdict held Merck liable for the death.
The jury awarded more than $250 million in total damages -- a $24 million penalty to Carol Ernst for mental anguish and and loss of companionship and $229 million in punitive damages.
Merck immediately said it would appeal the decision.
"There is no reliable scientific evidence that shows Vioxx causes cardiac arrhythmia, which an autopsy showed was the cause of Mr. Ernst's death," Merck attorney Jonathan Skidmore said.
