Joao Maria de Souza, 45, had been in bed with his wife Leni when the animal fell through the ceiling of their home in Caratinga, southeast Brazil.
The cow is believed to have escaped from a nearby farm and climbed onto the roof of the couple's house, which backs onto a steep hill on Wednesday night.
The corrugated roof immediately gave way and the one-and-a-half-ton animal fell eight feet onto Mr de Souza's side of the bed.