The nucleotide excision repair (NER) protein ERCC1 is part of a functional complex, which harbors in addition the repair correcting activities of ERCC4, ERCC11 and human XPF. ERCC1 is not associated with a defect in any of the known human NER disorders: xeroderma pigmentosum, Cockayne's syndrome or trichothiodystrophy. Here we report the partial purification and characterization of the ERCC1 complex. Immunoprecipitation studies tentatively identified a subunit in the complex with an apparent MW of approximately 120 kDa. The complex has affinity for DNA, but no clear preference for ss, ds or UV-damaged DNA substrates. The size of the entire complex determined by non-denaturing gradient gels (approximately 280 kDa) is considerably larger than previously found using size separation on glycerol gradients (approximately 120 kDa). Stable associations of the ERCC1 complex with other known repair factors (XPA, XPC, XPG and TFIIH complex) could not be detected.