The shoulder pain is one of the main causes that lead the patient to medical evaluation. Today, the ultrasound (US) represents an essential tool in the orthopaedical, rheumatological and rehabilitative setting to address the musculoskeletal causes of pain. Amongst the commonest causes of shoulder complains lay the frequent subacromial chronic bursitis (SACB). In this condition, the thickening of the bursal walls and subsequent fusion of the two synovial sheets leads to the reciprocal loss of bursal walls gliding under the subacromial space and consequently pain. This condition represents a common cause of shoulder pain and may be easily addressed by musculoskeletal sonographers. The purpose of this paper will be to describe the US appearance of SACB and to evaluate the efficacy of US-guided hydrodilation in its treatment. We included patients with painful shoulder attending our outpatient clinic for shoulder complains with the diagnosis of SACB with a bursal wall > 1.5 mm. A group was treated via US-guided hydrodilation, while the control group was treated via a classical blind approach using triamcinolone acetonide. Both groups underwent the same rehabilitation program following the injections. The shoulder functionality was assessed via qDASH questionnaire at baseline, days 3, 7, 14, 30, 60, and 90. A p <0.05 was considered significant. Both groups displayed a significant reduction of pain; nevertheless, in the group treated with US-hydrodilation, there was no need for re-treatment. The US-guided hydrodilation for SACB should be the preferred technique to detach bursal walls and improve patient symptoms, since it requires fewer invasive maneuvers.