The article represents the capsule review of the ontological constructions of the main trends of the Buddhist Philosophy: Sarvastivada, stating that only dharmas are real; Yogachara with its absolutization of the role of consciousness; Madhyamaka with its doctrine of the ineffability of reality. The article critically examines the statements of various modern researchers, such as Karunadasa, F. I. Scherbatskoy, J. Singh, and ancient philosophers, such as Vasubandhu and Nagarjuna, on the ontological problematics. In his article the author analyzes scrupulously the meanings of a number of Sanskrit philosophical terms and gives his own interpretations. He offers the peculiar explanation for the fundamental ontological principle of Sarvastivada: «Sarvam asti» – «Everything exists», that is all dharmas exist really, and in all three times. S.B. Berezhnoy considers also the first category of Madhyamaka Philosophy – Sunya – as the paradoxical notion that means both «Deficiency, Lack of Being» and «Fullness of Being».