She made her reappearance in a Guineas Trial last weekend, finishing third over seven furlongs while conceding weight. O'Brien has also entered Altair, winner of her only start to date, for the Classic on May 31. Both fillies are owned by Chantal Regalado-Gonzalez, who won the Oaks with 50-1 outsider Qualify in 2015.
Qualify was trained by O'Brien's father Aidan, who is responsible this time for 19 entries - which include Hermosa, Just Wonderful and Chablis.
Ralph Beckett, who has a good record in the race, has entered Manuela De Vega, Antonia De Vega and Dancing Vega.
There are three French fillies engaged - including Nicolas Clement's Wonderment, a Group One winner at Saint-Cloud in October.
"Wonderment has grown over the winter and looks a picture at the moment. I could not be happier with her," said Clement. "She was a Group One winner as a two-year-old. We have no doubts about her staying a mile and a half, and we think she will handle Epsom - which is why we decided to make the entry.
"She will start off in the Prix Penelope at Saint-Cloud on May 1 - and then depending on how she gets on there, we have the option of the Investec Oaks or the Prix de Diane."
Andre Fabre has entered Villa d'Amore and Tamniah. Others to note include Richard Hannon's Star Turn and William Haggas' Frankellina.
