It is in Mahayana, the dominant Buddhist tradition of East Asia, that the Medicine Buddha first appears. Veneration of this Lord of Healing became one of the most popular and widespread devotional groups.
According to Mahayana tradition there are infinite Buddhas, bodhisattvas, and deities. They represent various aspects of the absolute Buddha-nature, such as compassion, wisdom, power, and emptiness. The Medicine Buddha embodies the healing aspect.
The Medicine Buddha is the highest possible model of a healer. Among the 12 vows the Medicine Buddha is said to have taken is that of curing just by the invocation of his name or the thought of Him. He was worshipped as the dispenser of spiritual medicine that could cure spiritual, psychological, and physical disease.
But this Buddha is not worshipped simply for healing powers alone; he is the form of the Buddha-nature that we aspire to realize in ourselves. Through the practice of meditation on the Medicine Buddha, one can generate enormous healing power for self and for the healing of others.