QUEENSLAND Art Gallery's Prado blockbuster was billed as a coup for the state, driven by a significant interstate marketing campaign and the allure of some of the world's finest art.

But not even a last-minute rush over the weekend to see Portrait of Spain: Masterpieces from the Prado could have reversed the slow attendances for the $6 million, 15-week exhibition that ended yesterday.

While the gallery didn't have finalised figures for the closing weekend, it expected the exhibition's overall attendance would exceed 110,000. As of the close of business Thursday Portrait of Spain had registered a daily average of 1001 visitors, well short of the daily averages of 4433 for the 6th Asia-Pacific Triennial at Brisbane's Gallery of Modern Art and 3527 for Masterpieces from Paris at the National Gallery of Australia.

The figure represents fewer than half the daily averages of 2008's Picasso and his Collection at GOMA (2108) and 2010's Valentino, Retrospective (2028).

But QAG's acting director Suhanya Raffel on Friday said the exhibition of works from Madrid's revered Museo Nacional del Prado -- one of the most expensive shows held in Queensland -- was "a success without question".

"We were expecting that kind of figure and that's what we were projecting," she said.

"The Matisse: Drawing Life (which opened at GOMA last year) had the same sort of figures and so did Surrealism: The Poetry of Dreams (GOMA, 2011)."

The exhibition featured more than 100 works, including paintings by Velazquez, Goya, El Greco and Ribera. The $6m cost of the exhibition was split between QAG and Art Exhibitions Australia, with the help of sponsors that included Events Queensland.

It was opened in July by QAG's former director Tony Ellwood, who then went south to take up the directorship at the National Gallery of Victoria.

Raffel, who will continue as acting director until the search for Ellwood's successor is finalised, said Portrait of Spain was the second exhibition of Old Masters in the gallery's history and there was "no question" Brisbane audiences wanted to see these types of works.

She said there was a spike in attendances to the exhibit when the Hamburg Philharmonic Orchestra, Opera and Ballet performed as part of Queensland Performing Arts Centre's International Series.

At the time of the exhibition's opening, Prado director Miguel Zugaza said it was "not easy to bring all these works to the other side of the planet" and that it was Ellwood's "dynamic energy" that had convinced the Spanish museum to lend its pictures.

The most successful exhibition in QAG's history was the free 21st Century: Art in the First Decade at GoMA in 2010, which secured 451,041 visitors. The final weekend of Portrait of Spain coincided with the opening of an exhibition dedicated to Australian painter Ian Fairweather.