A couple in their 60s were taken to hospital by ambulance after colliding with an elk in Torsås municipality in Kalmar county, according to the police.
The woman's condition is critical and she is being treated at the hospital.
There is no suspicion of crime, and the incident is being investigated as an accident.
The alarm came at around 18:00 on Sunday. Traffic on the E22, where the accident occurred, was initially closed off but was back in operation about half an hour later.