Apollo butterfly is one of the most vulnerable Lepidoptera species in the Palearctic. Being widely distributed, it is represented only by the isolated populations over the whole area. The number of Apollo species is steadily declining, and nowadays it has become extinct in many European countries. Eastern Fennoscandia is one of the regions, where the population of this species has survived. In the regional lists of protected animals Apollo has the status of critically endangered butterfly. In Finland it is currently confined to the south-west coast of the Gulf of Finland and the Aland Islands, while in the Leningrad province and Republic of Karelia only a few modern records are known. This paper presents data on 111 specimens of Parnassius apollo from the collection of the Zoological Museum of Helsinki University, gathered in the Karelian biogeographic regions of Russia and Finland in 1901-1954, with references to modern place names. It is evident that Apollo has become extremely rare or extinct in the places where it was quite abundant in the middle of the XX century. The reasons of the sharp fluctuations and extinction are not clear, but rather related to the climatic features, than to human activities. Data on the distribution of Apollo in the past can be a starting point for the search of the possibly preserved populations in Ladoga Lake area and the islands of the Baltic Sea.