Cys-loop receptors, including the acetylcholine, glycine, 5-HT3 and GABA receptors, are molecular targets of general anesthetics and alcohols. Molecular mechanisms of anesthetics and alcohols interacting with Cys-loop receptors are still unclear. ELIC is a prokaryotic homolog of Cys-loop receptors and can be inhibited by general anesthetics and alcohols. Here, we report crystal structures (∼3.1 A) of ELIC bound with the volatile general anesthetic isoflurane, and bound with 2-bromoethanol. The crystal structures were obtained in the presence and absence of the agonist propylamine. Isoflurane was found inside the pore at two sites near T237(6′) and A244(13′), respectively, but 2-bromoethanol was only found near T237(6′). In addition, 2-bromoethanol also bound near Y102 and E150 in the extracellular domain. The presence of propylamine had no obvious effect on the binding sites for both isoflurane and 2-bromoethanol. This is the first time that an anesthetic or alcohol has been observed in the pore at an atomic resolution. The newly identified binding sites of isoflurane and 2-bromoethanol in ELIC are significantly different from previously reported anesthetic and alcohol binding sites. Neither isoflurane binding nor 2-bromoethanol binding introduced significant structural perturbation. The binding of isoflurane and 2-bromoethanol inside the pore suggests the possibility of channel occlusion as a mechanism for channel inhibition of Cys-loop receptors by general anesthetics and alcohols. Supported by grants from NIH.