The letters and postcards were written in the 1920s and 1930s to Garbo’s friend Vera Schmiterlöv.
Archive chiefs have reported the theft to the police.
“There has been a breakdown somewhere in our routines,” Per Clason, head of security at the Military Archives, told Swedish Radio.
Another letter from Garbo, which later turned out to be a copy, recently fetched 15,000 kronor at auction.
Front page Photo: Henry B. Goodwin/ Copyright: Royal Library/ Source: imagebank.sweden.se