A series of flavones and isoflavones were tested for their ability to inhibit reverse transcriptase of avian myeloblastosis virus (AMV).The inhibition of AMV reverse transcriptase was significant with quercetin, fisetin, myricetin or DN-24, whereas the effects of 7,8-hydroxyflavone, baicalein and morin were moderate.Apigenin, acacetin, DN-23, DN-25, genistein, biochanin A, D-(+)-catechin and α-naphthoflavone were of no or poor activity.Structure-activity relations are discussed.