Hematotoxic snake envenomation is clinically important and has serious complications. This case report describes the clinical manifestations of a bite from a newly described species of hematotoxic snake and the outcomes of treatment using locally available antivenom and supportive management. A 39-y-old male was bitten on his right ankle by an unidentified snake. The patient developed coagulopathy, rhabdomyolysis, and clinical signs of compartment syndrome of his right leg within the first day. Eight doses (30 mL, or 3 vials per dose), or a total of 240 mL, of hemato-polyvalent antivenin (Thai Red Cross, Thailand) were given. Aggressive intravenous hydration and alkalinization of urine were performed, and a fasciotomy was performed for the treatment of suspected compartment syndrome. The patient's clinical symptoms and laboratory results indicated progressive improvement during the 5 d of hospitalization. The snake was later identified as Protobothrops kelomohy, a novel snake species with no clinical data available regarding its envenomation of humans. This case shows that P kelomohy envenomation can produce severe effects that occur both locally and systemically. The benefits of the use of polyvalent antivenom in this situation were unclear. However, with supportive treatment in conjunction with serial clinical and laboratory monitoring, the patient recovered, albeit after 7 d of hospitalization.