Identification of early indicators of diagnosis and prognosis together with tight control of disease activity are the current goals of management of early arthritis. Several studies in the literature to date suggest that musculoskeletal ultrasonography (US) may have a role in this setting. US is a valid and reliable tool for the assessment of inflammatory arthritis - either as an ultra-sensitive measure of inflammation or joint damage. US is also useful in the differential diagnosis of early arthritis, both identifying disease specific findings and integrating clinical findings into structured diagnostic algorithms. Grey scale and power Doppler US are sensitive disease activity and severity markers, identifying subgroups of patients with poorer clinical and radiological outcomes, even once clinical remission has been achieved. The present review provides an update of the available data and discusses research issues of ultrasound imaging in early arthritis.