Streptococcus intermedius strain UNS 35, a brain abscess isolate, produced extracellular hyaluronidase when grown in brain heart infusion broth. Chemical assays with this enzyme indicated that hyaluronate depolymerisation resulted in the formation of carbohydrate moieties with N-acetylglucosamine at the reducing terminal and containing an unsaturated carbon-carbon double bond. The nature of the products of this hyaluronidase were investigated further by high-field (400 MHz) proton (1H) NMR spectroscopy. Treatment of hyaluronate with the enzyme resulted in a series of new, sharp resonances in spectra (acetamido methyl group singlets located at 2.03 and 2.07 ppm, sugar ring proton multiplets in the 3.5-4.2 ppm chemical shift range, and doublets at 5.16 and 5.87 ppm) characteristic of low-M(r) oligosaccharide species, predominantly those containing glucuronosyl residues with delta 4,5-carbon-carbon double bonds. Comparison of spectra acquired from hyaluronidase-treated samples with that of an authentic sample of 4-deoxy-L-threo-hex-4-enopyranosyluronic-acid-N-acetylglucosamine (delta UA GlcNAc) indicated that this disaccharide was a major product arising from the actions of this enzyme. When used in minimal media, hyaluronate supported growth of S. intermedius, with lactate as the major metabolic end-product.