Evidence that hairpin ribozymes function in the absence of bivalent cation cofactors suggests that active site nucleobases might participate directly in catalytic chemistry. We have adopted an abasic ribozyme rescue strategy to begin to dissect the roles of specific nucleobases in hairpin ribozyme activity. Loss of one active site nucleobase, G8, could be compensated by providing certain nucleobases and nucleobase analogues in solution. Comparison of the biochemical and structural features that are shared among small molecules that mediate rescue provides a new perspective on potential mechanisms of hairpin ribozyme catalysis.