We report on a patient with an incomplete tetraplegia below C2 who suffered from a post-traumatic abdominal spasticity, spasticity of the legs, and bladder contractions of high intensity. Breathing was possible during the day using accessory respiratory musculature. All standard therapeutic regimes against spasticity failed. Treatment was started with delta-9-tetrahydrocannabinol administered orally in a dosage of 2 x 2.5 mg/day. The spasticity of the legs and the bladder improved with the treatment. After 3 days, the patient complained about dyspnea and shortness of breath. Treatment with delta-9-tetrahydrocannabinol was discontinued after 5 days but the patient needed ventilatory support for 1 week. After 1 week, spontaneous breathing was possible again. The reasons for respiratory failure in endangered patients during treatment with delta-9-tetrahydrocannabinol could be effects such as sedation, combined treatment with baclofen, muscle weakness, or central nervous effects in the medulla oblongata.