Owing to the effectiveness of cisplatin in cancer chemotherapy, there is a growing interest in the development of other metal complex-based drugs. Similarly, the approval of photodynamic therapy and extracorporeal photopheresis in clinical practice, and the general advantages of temporal and spatial specificity inherent in phototherapy have generated a general interest in the development of other light-dependent treatment modalities. Over a decade ago it was demonstrated that the thermally inert octahedral bisbipyridyl complex cis-dichlorobis(1,10-phenanthroline)-rhodium(Ill) chloride (BISPHEN) could be activated by light and could then mimic the thermal chemistry between cisplatin and calf thymus-DNA. Thus, the term 'photocisplatin reagents' was coined for rhodium (and related) metal complexes that are thermally inert, but which form covalent bonds with DNA upon irradiation with ultraviolet/visible light. This review discusses recent developments in the elaboration of such photocisplatin reagents.