This study has been carried out to investigate localization of allatostatin-producing cells in the gut of Agrius convolvuli using an immunocytochemical method. Allatostatin-producing cells could not be found in the foregut and hindgut, but they were abundantly distributed only in the posterior part of midgut. These endocrine cells had typically columnar shape, with secretory surface positioned to muscular layer of midgut wall and also showed different intensity of immunoreactivity to AST, mainly with strong or moderate intensity.