The Guhyasamāja Tantra (Sanskrit: Guhyasamājatantra; Tibetan: Gsang ’dus rtsa rgyud (Toh 442); Tantra of the Secret Community) is one of the most important scriptures of Tantric Buddhism. In its fullest form, it consists of seventeen chapters, though a separate "explanatory tantra" (vyākhyātantra) known as the Later Tantra (Sanskrit: Guhyasamāja Uttaratantra; Tibetan: Rgyud phyi ma. (Toh 443)) is sometimes considered to be its eighteenth chapter. Many scholars believe that the original core of the work consisted of the first twelve chapters, with chapters thirteen to seventeen being added later as explanatory material.
In India, it was classified as a Yoga or Mahāyoga Tantra. In Tibet it is considered an Unexcelled Yoga Tantra (rnal ’byor bla med rgyud). It develops traditions found in earlier scriptures such as the Compendium of Reality (Sanskrit: Sarva-tathāgata-tattva-saṃgraha; De bzhin gshegs pa thams cad kyi de kho na nyid bsdus pa (Toh 479)) but is focused to a greater extent on the antinomian aspects characteristic of the later Buddhist Tantras. Naropa and Aryadeva considered the Compendium of Reality to be a root tantra in relation to the Guhyasamaja Tantra. The Guhyasamaja Tantra survives in Sanskrit manuscripts and in Tibetan and Chinese translation.
The Guhyasiddhi of Padmavajra, a work associated with the Guhyasamaja tradition, prescribes acting as a Saiva guru and initiating members into Shaiva Siddhanta scriptures and mandalas. Statues and pictures were also created to beautify the radical methodology.