A jittery groom shockingly fainted at the altar during his wedding ceremony in a frightening moment that was caught on video.

A clip of the scary incident shows Gustavo Schmitz, 23, standing with his bride-to-be Pamela Berto Schmitz, 25, while exchanging vows at the nuptials in Santa Catarina, Brazil on Saturday.

The couple was waiting to say 'I do' when Gustavo suddenly started swaying.

The overcome groom was then seen toppling backwards as the pastor rushed forward in a desperate attempt to save him.

Guests immediately rushed to the groom's side before one of his friends, a doctor, provided assistance and allowed the wedding to continue.