Summary Soybean cell suspension cultures grown on NH 4 + /NO 3 − as nitrogen source produce the ureides, allantoin and allantoic acid. We adapted cell suspensions to grow on these ureides and the purine degradation intermediates, inosine-5′-monophosphate (IMP) and uric acid, as sole nitrogen sources. The purine degradation inhibitors, allopurinol and allantoxanamide, blocked growth of the cell suspensions on intermediates prior to, but not after, the point of inhibition in the purine degradation pathway (the enzymes xanthine dehydrogenase and uricase, respectively). Both inhibitors also blocked incorporation of label from 14 C-labelled IMP into allantoin and allantoic acid. Ureide synthesis via purine degradation in the cell suspensions is generally similar to that reported for whole plant tissues, with the exception that IMP is degraded in the culture medium directly to hypoxanthine, rather than intracellularly to xanthine. The cell cultures described may be a useful system to study plant purine metabolism.