Helminthosporium victoriae, the causal organism of Victoria blight disease of oats, produces a host-specific pathotoxin (HV-toxin) in culture.1,2) It was suggested3,4) that HV-toxin was composed of aminoacids and the nitrogenous base victoxinine (I). The structure of victoxinine was elucidated by Dorn and Arigoni,5) but the structure of HV-toxin is still unknown. During attempts to isolate HV-toxin, we have found an easy method for detecting victoxinine derivatives using 5% vanillin in concentrated H2SO4. We have also isolated a new victoxinine derivative and determined its structure as victoxinine-α-glycerophosphate (II). In this report we wish to present evidence on the structure of victoxinine-α-glycerophosphate.