The Bloch-Wigner theorem over an algebraically closed field F determines a connection between the third homology of SL 2 (F) and the group describing the nontrivial relations on the tensors of the form x ⊗ (1 − x)(x ∈ F × \{1}). The purpose of this article is to provide a version of this theorem over rings with large number of unites, for examples semi-local rings with infinite residue fields.