Figures reveal that almost 300,000 fewer visitors went to the Riverside Museum which cost £59million when it opened less than three years ago.
Attendance figures tumbled last year to just 740,276 despite the Riverside being named as European Museum of the Year compared to 1,008,092 in 2012.
That's a drop of nearly 268,000 in the space of just 12 months.
But Glasgow Life, which runs the city's culture venues, shrugged off the 26.6% decline in numbers.
A spokesman claimed: "It was always expected that the Riverside Museum would record a drop in visitor numbers after enjoying massive success in its first few years."
It's a claim that's backed up by the Association of Leading Visitor Attractions. An ALVA spokesman said it was a "natural phenomenon" which often happened after new venues enjoyed a "honeymoon period."
But it was better news for Glasgow's top attraction. Kelvingrove Art Gallery & Museum attracted 1,044,067 visitors last year - up 6473 on 2012. The Riverside, like Kelvingrove and the city's other attractions, offers free entry.
And the ALVA spokesman pointed out that Kelvingrove had only just held its most successful art exhibition. The work of Scots artist Jack Vettriano attracted more than 123,000 visitors. The Glasgow Life spokesman added: "Glasgow's nine civic museums continue to perform exceptionally well with more than 3.1 million attendances in 2013."