This is the dramatic moment a grandmother's lightning-fast reaction saved a baby from a snake attack.

The grandmother was lying down with the boy in his playpen when the youngster curiously pointed at the serpent lurking near the door of their home in Uthai Thani, Thailand, on March 11.

The grandmother turned to look and was horrified to see the large snake rushing toward them.

CCTV footage shows the terrified woman screaming as she pulled her grandson aside just in time to avoid the fast-moving reptile. She then scooped him up and left the playpen, fearing the animal would return to attack them.

'I stood up instinctively when I saw the snake approaching,' said the grandmother, who pulled off the epic save.

'I kept my eyes on the snake then quickly pulled away my grandson just in time.'

The snake is believed to have attempted to strike the infant as it moved its head towards the boy's exposed legs. However, the youngster was pulled away and he was unharmed.

The reptile, believed to be a non-venomous but highly aggressive black rat snake, slithered through an open door and disappeared into the undergrowth.