Purpose: To determine the effect of atractylenolide-III (ATL-III) on loperamide-induced slow transit constipation (STC) in a rat STC model, and to elucidate the mechanisms involved. Methods: Male Wistar rats were divided into five groups (n=6 per group): normal control group (NG), model group, and three STC rat groups treated with different doses of ATL-III, viz, 5, 10 and 15 mg/kg. The rats were treated for 15 days. Feed consumption, fecal excretion and intestinal transit rate were determined. Nitric oxide synthase (NOS), somatostatin (SS), serotonin (5-HT), and vasoactive intestinal peptide (VIP) were measured with enzyme-linked immunosorbent assay (ELISA). The protein and mRNA expressions of C-kit, SCF, PKC, and PI-3K were assayed using Western blot analysis and realtime reverse transcription polymerase chain reaction (RT-PCR), respectively. Results: The amount, weight, and moisture content of stool, and water consumption were significantly higher in ATL-III-treated groups than in the untreated (model) group (p < 0.05), whereas no difference was observed in feed intake. Intestinal transit rate was higher in the ATL-III-treated groups (p < 0.05). Decreased NOS, SS and VIP levels and increased 5-HT level were seen in the ATL-III-treated groups (p < 0.05). ATL-III treatment also induced increases in smooth muscle cells, neuronal cells, and mucous layer (p<0.05). Results from RT-PCR and Western blot revealed that ATL-III–treated groups had elevated c-kit, SCF, PKC, as well as PI-3K mRNA and protein expressions (p < 0.05). Conclusion: These results suggest that ATL-III mitigates loperamide-induced STC in rats via stimulation of NOS, SS, VIP, and 5-HT secretions. It also increases smooth muscle cells, neuronal cells, and mucous layer, and regulates the signaling pathways involving PKC, PI3K, SCF, and c-kit.