The purpose of this study is to report the radiologic and clinical outcomes of arthroscopic intervention for isolated posterosuperior paralabral cysts and simultaneous treatment of cysts combined with associated shoulder pathologies. From March 2008 through December 2016, 70 cases (48 males and 22 females) operated on for symptomatic posterosuperior paralabral cysts were included. Mean age was 45 (range 18-69). These patients were classified into two groups depending on if they had accompanying lesions: Group I (isolated group, 27 patients) and Group II (concomitant group, 43 patients). Arthroscopic cyst decompression with a labral repair or posterior capsulotomy for patients without labral tear were performed. All concomitant pathologies were also operated simultaneously. Follow-up MRI were performed at postoperative 6 months and clinical outcomes were evaluated during the follow-up. Arthroscopic all intra-articular cyst decompression and labral repair was performed on 67 patients. In three patients, posterior capsulotomy without labral repair was performed for cyst removal. For 43 patients with concomitant lesions, 31 rotator cuff repairs, three SLAP repairs along with biceps tenodesis, two distal clavicle resections due to A-C joint arthritis, one calcific deposit removal, four Bankart repairs, and two acromioplasties were performed. The follow-up MRI showed complete cyst resorption except for two patients. The mean VAS, ASES, UCLA, SST and CS scores significantly improved at the last follow-up. Although both groups showed significantly improved range of motion after the surgery, improvement of ROM in Group II lagged at early periods of the rehabilitation. Arthroscopic labral repair with all intra-articular cysts decompression or simple posterior capsulotomy were both effective treatment modalities. If paralabral cysts were associated with other shoulder lesions, simultaneous treatment of combined lesions could be performed for the improved clinical outcomes at final follow-up with expected lag in the early rehabilitation period. Level III, Retrospective Comparative Trial, Treatment Study.