This corpus study presents a comparative quantitative analysis of the partitive-accusative alternation of object case in five Finnic languages, using Bible texts. Objects of finite, non-finite and impersonal verbs are discussed. It includes a comparison of the use of case in written old Estonian and Finnish, tracing changes through to modern times, with some historical data also from Karelian, Livonian and Veps. The nominative-partitive alternation of copula complements and subjects in existential clauses is also analysed synchronically and diachronically. The review of relevant literature, much of which is in Finnish or Estonian, and explanatory introductions in all sections, are especially useful for those starting to study Finno-Ugric languages, but also for typologists and historical linguists.