Objective(s) Ziziphora clinopodioides Lam. is a plant widely used in Iranian traditional medicine for gastrointestinal disorders. Several reports have demonstrated antibacterial (Helicobacteria pylori), antioxidant and antiinflammatory properties of Z. clinopodioides. The aim of this study was to investigate the effects of aqueousethanol extract of Z. clinopodioides on rat’s gastric acid output in basal, vagotomized (VX) and vagal stimulated conditions. Materials and Methods A total of 24 male Wistar rats weighed 200-250 g were randomly divided into two groups: control and test. Tracheostomy and gastroduodenostomy procedures were performed for each rat. In the vagotomized condition the vagus nerve in the cervical region was dissected and in the vagal stimulation condition the distal portion of the vogues nerve stimulated. Gastric content was collected for 15 min by wash out technique. A volume of 1 ml of three doses (0.5, 1 and 2 mg/kg) was introduced into the stomach (i.g.) of each rat in the test group and the same volume of saline was used in the control group. Total titratable acid was measured by a titrator. Results The extract inhibited acid secretion significantly at basal condition. At VX condition not only this inhibitory effect on acid secretion disappeared but also a stimulatory effect at the dose of 2 mg/kg was shown. In vagal stimulation condition the extract showed a significant inhibitory effect at 1 mg/kg dose. Conclusion Taking together our data resulted from comparison of three conditions showed that the extract exerted an inhibitory effect on acid secretion in basal and vagal stimulation. Also, according to our results this inhibitory effect of the extract could be exerted via gastric vagal parasympathetic nerve.