Harry Potter and the Prisoner of Azkaban has taken £5.3m in one day in the UK, more than any other film.
The third film in the Potter series opened in over 500 cinemas on 31 May, and took more than the first days of the first two films put together.
Meanwhile, author JK Rowling said it was her favourite Potter film so far.
Speaking on her website, jkrowling.com, she said: "I first saw Prisoner of Azkaban when it was barely finished. I loved it immediately."