The biosynthesis of valclavam was investigated by feeding radiolabelled potential precursors to fermentations of Streptomyces antibioticus ssp antibioticus TU 1718. The preliminary results indicate that the primary metabolic precursors of valclavam are L-valine, L-arginine, L-methionine and a 3-C pool metabolite and suggest a common biosynthetic origin for clavulanic acid and valclavam.