Sir,Attempt to decompress the stomach causing an “alarming” circuit leak.We would like to report a case of unusual circuit leak during conduct of anaesthesia, that occurred after insertion of nasogastric (NG) tube for gastric decompression. A 56-year-old male patient with a diagnosis of bilateral direct inguinal hernia was scheduled to undergo laparoscopic total abdominal preperitoneal repair under general anesthesia with controlled ventilation.The anesthesia workstation GE Datex Ohmeda Aisys was checked for leaks and integrity before the patient was wheeled into the theater. Our patient was induced with propofol 100 mg intravenous (i.v.) and vecuronium 5 mg i.v. and intubated with size 8.5 ID cuffed endotracheal tube. Volume controlled ventilation was initiated with a tidal volume 450 ml at a respiratory rate of 12 breaths/min. Fresh gas flows were reduced to 600 ml and end tidal agent monitored controlled flow (EndTidal Control in GE Datex Ohmeda Aisys) was started. After 5 min, a NG tube of size 16 FG was then introduced (on surgeon's request) in a blind fashion and gastric placement confirmed with auscultation over the epigastric area. Subsequently, the bellows collapsed, and there was a circuit leak alarm. The integrity of all circuit connections was checked. Vaporizer and soda lime canister, which had been refilled the previous day was also checked again for any improper assembly. We could not identify any other reason, which could be a potential cause of circuit leak.[1]We incidentally noticed that the closure of NG tube port reduced the amount of circuit leak. Tidal volume exhaled increased by about 70-100 ml. As the surgery had begun, and the abdomen was draped, we could not re-check the NG tube position by auscultation. When the NG tube port was dipped in a bowl of water, there was bubbling of air continuously. Removal of NG tube eliminated the circuit leak completely, and we could continue with volume-controlled ventilation with the initial ventilator parameters. It was then assumed that there was an inadvertent intratracheal placement of NG tube which resulted in a leak through the NG tube port as well as around the NG tube.We report a very unusual, innocuous cause of circuit leak, which lead to serious problems with mechanical ventilation. Confirmation of NG tube by epigastric auscultation method may not be a foolproof technique of its proper placement.[2] Though rare, it is important for anesthesiologists to be aware of such a cause of circuit leak.