Resonance Raman (RR) spectra are reported for the radical ions of the bacterial photosynthetic pigments bacteriochlorophyll a (BCh) and its metal-free analog bacteriopheophytin a (BPh). The radical anions, BCh(-) and BPh(-) were the primary focus of the RR study; however, the radical cation, BCh(+), was also examined. The RR data for all the radical species were acquired by using a variety of excitation wavelengths in the UV-violet region. Data were also obtained for BCh(+) and BCh(-) in solvents in which the Mg(II) ion axially coordinates either one or two solvent molecules. The RR data for the radical ions suggest that oxidation/reduction results in characteristic frequency shifts for the carbonyl and ring skeletal modes of the bacteriochlorin macrocycles. These frequency shifts provide benchmarks for the characterization of transient radicals in vivo via time-resolved vibrational spectroscopy. The oxidation/reduction-induced frequency shifts observed for BPh and BCh are indicative of significant structural and/or electronic perturbations of the bacteriochlorin macrocycle. The C-9=0 and the C-2a=O groups appear to be the key structural elements in these perturbations. The RR data further suggest that oxidation/reduction alters the forms of the vibrational eigenvectors of the carbonyl and ring skeletal modes. This in turn suggests that the relationship between the vibrational frequency shifts and structural and/or electronic perturbations is governed by the interplay of a number of subtle factors. Comparison of the RR data for the radical species in solution with those obtained from reaction center proteins suggests that the pigment-protein interactions may be significantly affected by cation/anion formation. Collectively, the RR data suggest that oxidation/reduction-induced changes in pigment-protein interactions could provide a means of mediating the redox properties of BCh and BPh in vivo.