A documentary by US director Laura Poitras, "All the Beauty and the Bloodshed," has won the Golden Lion award for best film at the 79th Venice International Film Festival.
This year's prizewinners were announced on the final day of the festival on Saturday.
Poitras's documentary is about US photographer Nan Goldin and her fight against the pharmaceutical industry over opioid painkillers. Deaths from opioid overdoses is a social problem in the United States.
Her film beat 22 other nominees in the competition category, including "Love Life" by Japanese filmmaker Fukada Koji.
"No Bears" by Iranian director Jafar Panahi was awarded a special jury prize.
Panahi is known for his works critical of the Iranian government, and was arrested in July.