The exhibit aboard the Queen Mary, which is moored in Long Beach, features items including hair rollers, suitcases, a lipstick holder and a "red shiny dress" that the iconic sex symbol supposedly owned. Thousands of people have paid $22.95 each to see it since it opened in November.
The lawsuit filed Friday in Los Angeles Superior Court, however, claims that Monroe had nothing to do with many of them and that some were made after she died from an overdose of sleeping pills in August 1962.
A spokeswoman for the Queen Mary and the exhibit declined to comment Tuesday to the Los Angeles Times, and the paper said it was unable to reach the items' owner, Chicago collector Robert W. Otto. He has previously insisted the items are authentic.
The lawsuit was filed on behalf of two people who attended the exhibit — Ernest Cunningham, author of "The Ultimate Marilyn," and Emily Sadjady. It asks that the Queen Mary and exhibit organizers be forced to refund admission fees and also seeks unspecified punitive damages.
"The Queen Mary should have done a little more homework," said the plaintiffs' attorney, George Braunstein.
The exhibit opened on the ship after the Hollywood Museum canceled a scheduled show over questions about the authenticity of some of the memorabilia.