Cholinesterase (ChE) activity was measured in the central nervous system (CNS) and in the digestive gland of the pestiferous land snail Achatinafulica Bowdich, by the method of Huegra et al. (1952). Acetylcholinesterase (AChE), and benzoylcholinesterase (BeChE) activity was higher in the former than in the latter. The complete inhibition of the enzyme activity with 10(-2) M eserine indicates that the ChE examined is AChE. The Km values of the AChE from the digestive gland and the CNS were 3.1 x 10(-5) and 9.0 x 10(-5) (M), respectively. The enzyme is the most active at pH 8.2 and 37 degrees C up to 60 min.