The experts from top British university King's College, London, based the ratings on factors including voice, eye contact, body language and excitement.
At the bottom of the list was TITANIC, with the boffins claiming there was no sexual chemistry between stars Kate Winslet and LEONARDO DiCAPRIO.
A King's College psychiatrist explains, "In Titanic, the way they speak to each other isn't natural. It just doesn't come across as genuine."
The top five films for sexual chemistry:
1. WHEN HARRY MET SALLY (MEG RYAN/BILLY CRYSTAL) - 10/10
4. LOST IN TRANSLATION (SCARLETT JOHANSSON/BILL MURRAY) - 9/10