This master's thesis deals with conspiracy theories that started circulating on the internet at the time of the novel coronavirus pandemic, from a folkloristic perspective. The author reviews conspiracy theories, that frequently appeared on social media platforms, forums, and other websites. She then classifies them according to their subject matter into three groups: conspiracy theories about the origin and spread of the virus, conspiracy theories about the government's involvment in the pandemic and conspiracy theories about measures to contain the spread of the virus. She also discusses the question of function of conspiracy theories, who believes and spreads conspiracy theories, what social fears do they express and how they can diminish tensions that are generated in times of great social change.