During the arthroscopic surgery of the shoulder, there was extravasation of fluid into the surrounding soft tissue due to the use of pressure pump irrigator. Clinically, the shoulder region became tense and intramuscular pressure of the deltoid could be elevated. To analyze the change of the intramuscular pressure of the deltoid and the efficiency of cryotherapy in the shoulder arthroscopy with pressure pump, we studied 35 consecutive patients who underwent various arthroscopic shoulder procedures at the Dankook University Hospital. We monitored intramuscular pressure using spinal needle connected to the patient monitoring system during arthroscopic procedures and postoperative period until return to preoperative pressure level. Twenty-seven patients were fitted with a cryotherapy. device in the operating room, and 8 were not according to the patient opinions. We evaluated the effect of cryotherapy with visual analog scales and amounts of analgisics for 3 days postoperatively. The results were followed; 1. Intraoperative highest intramuscular deltoid pressure was 293mmHg (average 169±68mmHg, 71293mmHg). 2. Immediate postoperative deltoid pressure was average 58.3±28.1mmHg (24-145mmHg). 3. Average time that the pressure had returned to the preoperative level was 114.3±38.6 minutes (p<0.05). There were no statistically significant between two groups, 113.9±41.1 min in the cryotherapy group and 115.7±32.6 min in the non-cryotherapy group. 4. Shoulder pain was less in the cryotherapy cases until second postoperative day. In conclusion, arthroscopic surgery of the shoulder can be performed with minimal complication in spite of high intramuscular deltoid pressure. More than 60 minutes may be needed for returning to normal intramuscular deltoid pressure. Cryotherapy is eftective in the pain relief but cannot minimize swelling postoperatively.