Opium poppy, Papaver somniferum L, is one of the ancient herbal medicines. In addition to this medical use of latex, opium that is extracted from the immature seed capsule, it is also used illegally for pleasure. It is being produced in great quantities in Turkey especially in Afyonkarahisar city. The seeds of opium poppy plant have high ratio oil content. The opium poppy seeds and oil of these seeds are purely used as an ingredient in production of bakery products. In this study, biodiesel evaluation of the opium poppy seeds that have a high oil ratio is aimed. Alkali catalyzed (NaOH) single-phase reaction was preferred to produce biodiesel from opium poppy oil. The parameters like catalyst concentration, methanol ratio, reaction temperature were optimized and biodiesel production was obtained with high yield in reaction time of 75 min. The methyl ester content in the opium poppy oil biodiesel was determined with Gas Chromatography-Frame Ionized Detector (GC-FID). In optimum conditions, methanol ratio and catalyst concentration was determined as 20 wt% and 0.5 wt%, respectively. The reaction temperature was optimized as 60 degrees C. Biodiesel was obtained from the opium poppy oil under optimum conditions. Some basic features of the produced methyl esters were determined. (C) 2011 Elsevier Ltd. All rights reserved.