Research at the Kentucky Tobacco R&D Center (KTRDC) focuses on the development of technologies for the production of plant-made pharmaceuticals and industrial products (PMPs and PMIPs) in genetically modified (GM) tobacco. Topping tobacco plants (removing flower buds) is an accepted method for containment of GM tobacco plants that are grown in field trials. Topping is used in conjunction with distance requirements from other tobacco to reduce or eliminate the availability of pollen for cross-hybridization which could result in a loss of containment. This project assessed the effectiveness of topping as a strategy for containment by removing the tops of randomly selected KTRDC hybrids and fertile tobacco plants to assess the potential for continued flower maturation and seed production. Removed flowers were left in the field or placed in a growth chamber under optimal production conditions. Flowers were monitored for development and seed production. Results suggest that removed flowers will continue to mature, produce pollen and produce seed. For containment of GM tobacco it may be helpful to remove topped flowers from the field or make sure they are not viable if left in the field.