Technical Abstract: Seven prenylated stilbenes were identified by combined HPLC-PDA-APCI-MSn analysis of an extract of mucilage from peanut (Arachis hypogaea L.) root tips. The principal constituent was assigned structure 7 (Fig. 3). The common name 'mucilagin A' is proposed for this novel compound. Its concentration in the mucilage was 250 'g g-1. The large body of literature on the antimicrobial properties of plant-derived stilbenes suggests that compounds detected in peanut mucilage may play a role in regulating root-soil pathogen interactions.