Burglars have stolen communist-era medals and jewellery from the Stasi Museum in Berlin, housed in the former secret police headquarters.
The break-in happened just six days after diamonds worth millions of euros were stolen from the Green Vault, part of a former royal palace in Dresden.
The items stolen in Berlin are worth "a few thousand euros", museum director Jörg Drieselmann told the BBC.
The Stasi had a huge network of spies and informers in former East Germany.
"Eight or nine orders were stolen," Mr Drieselmann said, but some of the medals were facsimiles, and "the physical damage done during the break-in costs more than what was stolen".
Among the items stolen were an Order of Karl Marx and an Order of Lenin.
Mr Drieselmann said the jewellery taken was a pair of earrings, a ring with pearls and gems, a gold watch and a gold timepiece.
The burglars broke in through a ground-floor window on Saturday night, using a nearby roof, and are now on the run.
Part of the museum is the former office of Stasi chief Erich Mielke, preserved as demonstrators found it when they stormed the Stasi building in January 1990.
When the communist East German state collapsed, after the fall of the Berlin Wall in November 1989, the Stasi was found to have many precious items confiscated from dissidents.
Mr Drieselmann said most of those valuables were later returned to the owners, but some items were not claimed, so they were put on display in the museum.
In some cases the Stasi sold confiscated jewellery in the West to earn much-needed hard currency.
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Mr Drieselmann said the burglary lasted only about 15 minutes and guards were not keeping a permanent watch throughout the night.
Police investigating the much bigger Dresden burglary of 25 November have offered a €500,000 (£427,000; $551,000) reward for information leading to the suspects or the recovery of the stolen gems.