We have used human single chain Fv (scFv) phage display antibody libraries to isolate recombinant antibodies against the DNA adduct 8-oxi-2'-deoxyguanosine (8-oxodG). One of these scFvs (175G) bound to several 8-oxodG-containing oligonucleotides whilst demonstrating no cross-reactivity with G-containing control oligonucleotides, and bound to 8-oxodG; lesions introduced into DNA by treatment with methylene blue and white Light. In addition, 175G inhibited the cleavage of an 8-oxodG-containing oligonucleotide by the Escherichia coli enzyme formamidopyrimidine-DNA glycosylase (Fpg). The nucleotide sequence of the 1756 V-H gene segment was 98% homologous to the published V-H sequence of a human hybridoma derived from a patient with systemic lupus erythematosus (SLE). Sera from two SLE patients bound to damaged DNA, and this binding could be inhibited by 175G. The use of human scFv phage display libraries has thus produced a unique reagent with specificity for 8-oxodG which may have a role in damage detection and quantitation and in modifying DNA repair activity. 175G also offers support to the hypothesis that SLE might be associated with oxidative damage to DNA