Guru Rinpoche Mantra is a sacred 12 syllable mantra. It is pronounced "om ah hung benza guru pema siddha hung." 

Enjoy reciting this potent mantra for clearing away perceived obstacles and calling on the power of compassion and wisdom of Guru Rinpoche which represents your own awakened mind. The sound alone of Guru Rinpoche mantra can quiet the mind and nervous system, relax the body, and connect you to the the nurturing energies within. 

There are many levels of meaning:

On one level:  

"OM AH HUNG" are seed syllables that have a connection to body, speech and mind. "Benza," or Vajra, refers to the indestructible diamond or thunderbolt heart. "GURU" is teacher. "PADMA" is lotus. And "SIDDHI" is the blessing. Finally "HUNG" often comes at the end of mantras.

On another level:

"Born in the North-west of the land of Oddiyana, On a pollen bed of a lotus stem, 

Wonderously you attained supreme accomplishment, 

You are renowned as the Lotus-born, surrounded by retinues of many dakinins, 

Emulating you I will perfect myself- come then I pray, bestow your blessings, 

GURU PADMA SIDDHI HUNG"