Idiopathic adhesive capsulitis is a common but poorly understood cause of a dysfunctional painful shoulder affecting daily routine. A prospective study comparing the functional outcome following hydrodilatation with manipulation and manipulation alone for idiopathic frozen Shoulder was undertaken. 158 patients (168 shoulders) with idiopathic adhesive capsulitis were treated with manipulation alone and hydrodilatation with manipulation. 88 shoulders underwent hydrodilatation with manipulation and 80 shoulders with manipulation alone. The initial evaluation included the recording of a detailed history and assessment of pain, range of motion, and function. The outcome evaluation included assessment of pain, range of motion and function; Oxford Shoulder Scoring and completion of the Disabilities of the Arm, Shoulder, and Hand (DASH) Questionnaire. The mean duration of follow-up was twelve months. With Hydrodilatation plus manipulation 77% patients had a satisfactory outcome, 20% had fair outcome and 3% were not satisfied with the treatment. With manipulation alone 52% patients had a satisfactory outcome, 45% reported a fair outcome and 3% were not satisfied with the treatment. Hydrodilatation is a simple and effective add on to the routinely done manipulation procedures to obtain better results.