Pregabalin is often used for the treatment of neuropathic pain in patients with spinal cord injury (SCI). We reported a patient with C5 [S(C5/C6)] ASIA Impairment Scale C SCI due to cervical myelopathy who presented CO2 retention when taking a therapeutic dosage of pregabalin. An 88-year-old patient with cervical SCI was transferred to the department of physical medicine and rehabilitation. When he had transferred, his neuropathic pain had been treated with 150-mg pregabalin per day (75 mg twice a day); however, he still exhibited severe neuropathic pain with a Numeric Pain Rating Scale score of 7 to 8. Dosage for the pregabalin increased from 150 mg/d (75 mg twice a day) to 225 mg/d (150 mg at morning and 75 mg at dinner). That afternoon, he presented drowsiness and confusion, and arterial blood gas analysis (ABGA) demonstrated respiratory acidosis with CO2 retention; pH, 7.312; PaCO2, 62.8 mm Hg; PaO2,58.9 mm Hg; HCO3 concentration, 30.8 mmol/L; base excess, 3.2 mmol/L; and oxygen saturation, 90.4%. Finally, he required tracheal intubation and ventilation. After 6 weeks, the patient was transferred to a general ward, and the follow-up ABGA and end-tidal CO2 showed normal range with the discontinuation of pregabalin. We demonstrated CO2 retention via ABGA in a patient with SCI due to cervical myelopathy who developed hypercapnia after taking a therapeutic dose of pregabalin. Physicians should pay particular attention to CO2 retention when prescribing a therapeutic dosage of pregabalin in a patient with cervical SCI.