Museum bosses are unable to locate a sculpture by world famous artist Auguste Rodin, said to be worth £3m.
Officials at Glasgow Museums said a plaster version of Le Bourgeois de Calais was purchased in 1901.
However, the sculpture is among almost 1,750 items currently listed as missing or stolen.
The charity that runs the city's museums said it was known to have been damaged after it was put on public display after World War Two.
Glasgow Life confirmed the sculpture is currently listed as "unlocated".
Rodin - who later became famous for his "Thinker" sculpture - was allowed by French law to manufacture different versions of "Le Bourgeois" in plaster and bronze.
A life-size bronze version of the sculpture takes pride of place in the gardens of the Houses of Parliament in London.
The plaster version is known to have been displayed in Kelvingrove Park in 1949 for the Sculpture in the Open Air exhibition along with another Rodin work, Saint jean de Baptiste.
Officials said Le Bourgeois is known to have been damaged during this exhibition and its whereabouts are currently unknown. The other sculpture is in storage at the Glasgow Museums Resource Centre.
The loss was described as '"utterly shameful" by the Paris-based Comite Rodin, which publicises and catalogues Rodin's work.
Jerome Le Blay, the Comite's director, said: "We lose a bit of humanity when we lose a work of art.
"Museums may have 100,000 items, so occasionally things get dropped or get lost in shipping. Art is often destroyed in acts of war - that's life - but when it goes missing as a result of mishandling or mismanagement by people it is utterly shameful.
"It really is deeply disappointing to discover Glasgow has lost art of this significance and importance."
Improved cataloguing
A spokesperson for Glasgow Life told OceanNewsUK Scotland News it had spent 20 years "conducting an inventory" of items in its collection which has included finding objects previously listed as lost.
"The process of recording, cataloguing and caring for the Glasgow Museums Collection has improved significantly since it was founded in the 1860s," the spokesperson said.
"For 30 years, the cataloguing of the collection has been increasingly centralised using the Museum's Collection Management System.
"As part of the major museums capital projects in Glasgow over the last 20 years, the storage of the collection has also been improved."
Le Bourgeois de Calais depicts the plight of the French port's residents during an 11-month siege by the English during the Hundred Years War in the late Middle Ages.
The burghers (Le Bourgeois) offered up their lives if their town could be spared.
