The Multi-State Lottery Association says the ticket matched the six numbers drawn Wednesday night. The winning numbers are 13, 26, 39, 41, 42 and the Powerball number 10.
It hasn't been announced yet where in Iowa the winning ticket was sold or who bought it.
Another ticket bought in Iowa is worth $1 million. It matched the first five numbers but missed the Powerball number.
An Iowa Lottery spokeswoman didn't immediately return messages from The Associated Press early Thursday.