Authorities in Saxony Anhalt said the A/H1N1 virus had been confirmed in a man who returned from Mexico last week. It's the second confirmed case of the virus in the eastern state.
Health officials said the patient from the town of Wittenberg had complained of a slight cold during a routine medical check. He has since been isolated at his home and is in good health, they said.
The Robert Koch Institute in Berlin said that despite a "certain stabilisation" of the situation, Germany had to be prepared for further infections.
The World Health Organisation has reported more than 1,800 confirmed cases of swine flu in 24 countries since the outbreak began in Mexico two weeks ago.
German airline TUI has cancelled all flights to Mexico City until May 31 due to the outbreak, the company said on Tuesday. Customers have been offered a free booking change. The airline will continue to fly to the Cancun, Mexico airport, which is some 1,200 kilometres from the country's densely populated capital.