Treatment for idiopathic adhesive capsulitis or frozen shoulder of the shoulder is controversial. The hypothesis of the study is that intra-articular corticosteroid injection in the early stages of idiopathic adhesive capsulitis will lead to a rapid resolution of stiffness and symptoms. This is a retrospective cohort study of only patients with stage 1 or stage 2 adhesive capsulitis. The diagnosis was made by history and physical examination and only when other causes of pain and motion loss were eliminated. Stage 1 adhesive capsulitis was defined as significant improvement in pain and normalization of motion following intra-articular injection. Stage 2 included patients who had significant improvement in pain and partial improvement in motion following injection. Seven patients with stage 1 and 53 patients with stage 2 comprised the baseline cohort. The mean age was 52 years (range: 30 to 78); 46 patients were female and nine patients had diabetes mellitus. Patients completed a physical examination as well as a shoulder rating questionnaire for symptoms and disability. Criteria for resolution were defined as forward flexion and external rotation to within 15 degrees of the contralateral side and internal rotation to within three spinal levels of the contralateral side. Forty-four of the patients out of 60 met the criteria for recovery at a mean of 6.7 months. The mode and median time to recovery was 3 months. The mean score at final follow-up for 41 patients using the shoulder-rating questionnaire of L'Insalata was 90 (range 52-100). The mean time to recovery for the stage 1 patients was 6 weeks (range: 2 weeks to 3 months), and it was 7 months for stage 2 patients (range: 2 weeks to 2 years). Glenohumeral corticosteroid injection for early adhesive capsulitis may have allowed patients to recover motion at a median time of 3 months. In many cases, the patients had improvement prior to the 3-month mark; however, that was the routine time for follow-up. Patients with stage 1 disease tended to resolve more rapidly than stage 2 patients. Prompt recognition of stage 1 and stage 2 idiopathic adhesive capsulitis and early injection of corticosteroid with local anesthesia may be both diagnostic and therapeutic.