Fourteen people were taken to hospital following the incidents that took place outside the city of Piteå.
None of the injuries are believed to be serious.
In the first crash, two buses - including a school bus with 37 people on board -collided. Eleven people were taken to hospital.
In the second incident, a school bus hit another vehicle. Three people had to be taken to hospital.
Treacherous road conditions in the area, and temperatures of around minus 20 degrees Celsius are believed to have been likely contributory factors in the accidents.