Shot in February 1996, when Winslet was just 19, the test was filmed with Winslet acting opposite 'Six Feet Under' and 'Law & Order' star Jeremy Sisto playing Jack Dawson, in lieu of her yet-to-be-announced leading man Leonardo DiCaprio.
[Related story: James Cameron: 'Titanic kiss out of focus']
Watch Kate Winslet in action in the video below:
Apparently 20th Century Fox, the studio behind the movie, wanted Matthew McConaughey for the leading man, but director James Cameron insisted on DiCaprio.
This was among three tests she did for Cameron all filmed in period costume. Cameron says that as soon as she appeared on screen, she was the obvious choice for the role.
Showing she could carry the lead in a Hollywood blockbuster, her performance helped the record-smashing film win 11 Oscars, including Best Picture and Best Director, as well as ushering her into the Hollywood A-list.
'Titanic' is released on Blu-ray today.