The working effect of Gastrin, neostigmine and prostaglandin in regard to the emptying of the stomach was tested on 31 dogs that had undergone a truncular vagotomy. Gastrin and neostigmine were proved to increase the motility at the stomach pylorus but was not able to bring about a coordinated emptying pattern. Prostaglandin shows different effects on the emptying reflex of the stomach. PGF 2 alpha increases the motility on the measuring marks, but at different time intervals. Because of this a coordinated motility is made possible.