Encouraging yields of thebaine have been obtained from Papaver bracteatum grown in Ireland. However climatic conditions adversely affect flower (and subsequent capsule production). Twelve vigorously flowering ornamental cultivars labelled P. orientale or "oriental poppy" were screened for the presence of thebaine. Five of the cultivars had no detectable thebaine. The thebaine content of the remaining 7 cultivars was determined. The capsules of the cultivar "Goliath" had a thebaine content of 3.0%. The identity of the thebaine was confirmed by isolation and examination of spectral evidence. In addition the two known N-oxides of thebaine were isolated and characterised from cv. Goliath. The combination of this chemical evidence and stomatal pore length measurements indicate that the plant labelled P. orientale cv. Goliath is closely related to P. bracteatum Lindl . This cultivar shows promise as a source of thebaine and has a potential in the hybridisation of genuine P. bracteatum to improve its flowering characteristics in mild climates.