Arthroscopic surgery has improved greatly over the past decade. Treatment of various juxta-articular disorders around the shoulder have benefited from endoscopic approaches. Cystic lesions of the shoulder on the scapular side have been treated in this way. This article describes a case of a 29-year-old patient with a unicameral bone cyst on the posterior aspect of the humeral head. Arthroscopic visualization using an accessory posteroinferior portal localized the cyst through the bare area of the humeral head. A cannulated burr was used to create an opening through the cortical wall between the cyst and the joint, and a careful curettage was performed. The cavity was filled with a demineralized bone matrix enriched with autologous blood packed into an arthroscopic cannula and delivered through the accessory portal. The patient reported pain relief immediately postoperatively and at follow-up. This case demonstrates the feasibility of arthroscopic treatment of a simple bone cyst of the humeral head. We believe that the knowledge of the juxta-articular anatomy allows the applications of scope-assisted procedures to be expanded, maximizing the results of a technique that allows a shorter recovery and less painful rehabilitation.