Nuclear respiratory factor 1 (NRF-1) is one of the key transcriptional activators for nuclear-coded genes involved in mitochondrial biogenesis and function as well as for many housekeeping genes. A transcriptional co-activator PGC-1 and its related family member PRC have previously been shown to interact with NRF-1 and co-activate NRF-1. We show here that NRF-1 can also directly interact with poly(ADP-ribose) polymerase 1 (PARP-1) and co-purify the PARP-1.DNA-PK.Ku80.Ku70.topoisomerase IIbeta-containing protein complex. Our in vitro binding experiments show that DNA-binding/dimerization domain of NRF-1 and the N-terminal half of PARP-1, which contains two Zinc fingers and the auto-modification domain, are responsible for the interaction, and that this interaction occurs with or without PARP-1 poly(ADP-ribosyl)ation (PARylation). DNA-bound NRF-1 can form a complex with PARP-1, suggesting that NRF-1 can recruit the PARP-1.DNA-PK.Ku80.Ku70.topoisomerase IIbeta-containing protein complex to the promoter. PARP-1 can also PARylate the DNA-binding domain of NRF-1 and negatively regulate NRF-1.PARP-1 interaction. Transient transfection and chromatin immunoprecipitation experiments suggest that PARP-1 plays a role during transcriptional activation by NRF-1. Our finding identifies a new aspect of transcriptional regulation used by NRF-1.