Tobacco use in films is falling, a US report on smoking in movies has found.
Yet its authors claim smoking still features in too many films and could be influencing young people to take it up.
"There's a declining trend which is good to see," said Ursula Bauer of the Center for Disease Control. "But we haven't made nearly enough progress."
The research is based on how many times tobacco use was shown in the biggest-grossing US films released between 1991 and 2009.
According to the study, there were 1,935 instances of smoking in all the films ranked in the US weekly box office Top 10 last year.
This compared with almost 4,000 instances in the biggest-grossing films of 2005.
The report recommends that movie ratings take into account smoking scenes and suggests that strong advertisements about the dangers of the habit precede such films.
Lead author Stan Glantz, of the University of California, said the report showed Hollywood was "perfectly capable of making movies without as much smoking and people still come see them".