Leigh syndrome is an extremely rare disorder in infants and children. It is characterized by a progressive neurodegenerative course with subacute necrotizing encephalomyelopathy, and it presents with developmental delay, seizures, dysarthria, ataxia, and myopathy. We present a patient with Leigh syndrome who required general anesthesia for percutaneous endoscopic gastrostomy. The respiratory, cardiac, and renal system functions should be very carefully evaluated in the peroperative period. The use of long-acting opioids and neuromuscular agents increases postoperative respiratory complications related to neuromuscular myopathy. Considering that lactic acidosis can develop in the perioperative period, it is recommended to give pre-perioperative fluids with dextrose.