An HMG2-like protein was purified from nuclear extracts of adult Schistosoma mansoni. Investigation of the amino acid composition of the schistosome HMG2-like protein showed that glutamic acid, glycine, aspartic acid and lysine were the most abundant. Carbohydrate analysis showed that the HMG2-like protein presented a low degree of glycosylation, galactose or glucose being the major monosaccharide constituent. Incubation of live schistosomes with 32P followed by isolation of nuclear proteins showed that the HMG-2 like protein could be phosphorylated. Partial sequence analysis of cyanogen bromide peptides revealed the occurrence of a phosphorylation consensus motif. The schistosome HMG2-like protein was found to bind preferentially to single-stranded DNA. The results suggest that the major non-histone S. mansoni nuclear protein belongs to the HMG family.