The accident in Spain's Alicante region happened when the woman noticed that a vase containing flowers had fallen from a nearby grave.
As she tried to turn the vase upright however, the marble tombstone she was leaning on for support gave way, Spain's Las Provincias newspaper reported.
She then fell two metres (7 feet) into a grave, while the tombstone smashed the lid of a coffin belonging to man buried several years earlier.
The elderly woman found herself in a kneeling position and was unable to find her way out of the grave.
She was eventually rescued by police and taken to a local hospital where she was treated for her leg injuries.