The Trikāya doctrine (Sanskrit, literally "Three bodies"; 三身 Chinese: Sānshēn, Japanese: sanjin, Tibetan: སྐུ་གསུམ, Wylie: sku gsum) is an Mahayana Buddhist teaching on both the nature of reality and the nature of a Buddha.

The doctrine says that a Buddha has three kāyas or bodies:

Even before the Buddha's Parinirvāṇa the term Dharmakāya was current. Dharmakāya literally means Truth body, or Reality body.

In the Pali Canon the Buddha tells Vasettha that the Tathāgata (the Buddha) was Dharmakāya, the 'Truth-body' or the 'Embodiment of Truth', as well as Dharmabhuta, 'Truth-become', 'One who has become Truth'

The Buddha is equated with the Dhamma:

Putikaya, the "decomposing" body, is distinguished from the eternal Dhamma body of the Buddha and the Bodhisattva body.

The Dharmakaya-doctrine was possibly first expounded in the Aṣṭasāhasrikā prajñā-pāramitā (The Perfection of Insight In Eight Thousand Verses), composed in the 1st century BCE.

Mahayan Buddhism introduced the Sambhogakāya, which conceptually fits between the Nirmanakaya and the Dharmakaya. The Sambhogakaya is that aspect of the Buddha, or the Dharma, that one meets in visions and in deep meditation. It could be considered an interface with the Dharmakaya.