INTRODUCTION. A detailed clinical examination and investigations are required to evaluate the cause of persisting groin pain following a metal on metal (MoM) hip replacement. Adverse reaction to metallic debris (ARMD) is an emerging problem with MoM hip replacements. It is an umbrella term encompassing metallosis, pseudo-tumors and aseptic lymphocytic vasculitis associated lesions (ALVAL). The role of imaging in the diagnosis of this complex problem is still unclear. A study was undertaken to evaluate the efficacy of ultrasound in diagnosis of ARMD following a MoM hip replacement. METHODS. The study group included 35 patients with a clinical and histological diagnosis of ARMD, who had a preoperative ultrasound. All ultrasound procedures were performed on the anterior and lateral aspects of the painful hip with a high frequency probe of 9–13 MHz (Sonoline Antares – Siemens). RESULTS. All patients diagnosed with ARMD had abnormalities identified on ultrasound. Fluid inside the joint was noted in 30 out of 35 procedures (85.7 %). Fluid outside the joint was noted in 33 procedures (94.3 %). Amongst the patients with fluid outside the joint, 32 had iliopsoas and 30 had trochanteric bursitis. Echogenic reflections were noted in 31 out of 35 procedures (88.6 %). Considerable attenuation or absence of iliopsoas and gluteus tendon reflection was seen in many patients with echogenic fluid collections on the anterior and trochanteric aspects of hip. Progression of such changes was noted on further 5 patients, who had a repeat ultrasound within an interval of 3–6 months. 1 patient had a progression from anechogenic to echogenic joint effusion. DISCUSSION. Different radiological investigations including MRI scan have been used for evaluation of painful MoM hip arthroplasty. To our knowledge, this is the first study to demonstrate the efficacy of ultrasound in diagnosis of ARMD. Floating echogenic reflections and fluid collections around iliopsoas and gluteus medius/minimus tendons is highly suggestive of ARMD. Ultrasound is a cheap, non-invasive and dynamic investigation and has been shown to be reliable in diagnosis of ARMD