Summary Atropine esterase activity in the regenerated plants of Duboisia myoporoides was determined during development and compared with that of seedlings. High esterase activity was found in the roots of seedlings throughout growing, whereas the activity in the roots of regenerated plants was extremely low at the early stages of development, though after regeneration when they were 6-months old the activity was recovered at the levels found in seedlings. The relationship between tropane alkaloid content in the leaves and atropine esterase activity in the roots of regenerated plantlets was examined. The results showed that extremely low activity in the roots seemed to be due to no or low accumulation of alkaloids in the leaves. Alkaloid dynamics in D. myoporoides were discussed.