Ureteroscopic holmium: yttrium-aluminium-garnet (Ho:YAG) laser lithotripsy is an excellent treatment modality, especially for a large impacted ureteral stone. The treatment is efficient and safe. It helps surgeons to carry out a minimally invasive lithotripsy instead of an open surgery in patients with ureteral calculi. Here, we present the first report of a fatal gas embolism that occurred during ureteroscopic Ho:YAG laser lithotripsy under spinal anesthesia. When this complication occurs, the correct crisis resolution protocols, such as prevention of further air entry, reduction in the volume of air entrained, well-hydration, and rapid initiation of cardiopulmonary resuscitation with administering inotropic drugs, are highly effective in the critical period.