EN
The present paper deals with the types of Indo-European diathesis, trying to define their origins and characterize the variations in the development of individual languages Contrastive analysis of Latin and Greek as languages with extremely dissimilar system of voices serves as the starting point. Diachronically both systems are different paradigmatizations of underlying common Indo-European structure. The reconstructed proto-diathesis consists of verb classes of agentive vs. non-agentive/inactive verbs with different series of endings. The Greek system of elaborated active vs. middle-passive oppositions cannot be projected into Proto-Indo-European. Latin, unlike Greek, attests archaic types of voices: r-deagentive (impersonal passive) and passive preterit with -to-participle which was the first Indo-European expression of the passive.