Patients suffering from hip osteoarthritis (OA) are frequently symptomatic, and the disease can result in significant limitation of patients' activity and high social costs. Hip OA is generally managed with systemic treatments such as nonsteroidal anti-inflammatory drugs (NSAIDs) and/or symptomatic slow acting drugs. Viscosupplementation with hyaluronan (HA) or its derivatives, which aims to restore the physiological and rheological features of the synovial fluid to improve symptoms, is now a routinely prescribed treatment for OA of the knee. However, few data exist in the literature regarding the use of viscosupplementation in the treatment of hip OA. The objective of this prospective, open, uncontrolled pilot study was to investigate the safety and effectiveness of intra-articular injection, under ultrasound control, of hylan G-F 20 for the treatment of OA of the hip. Twelve patients (> or =40 years old) with symptomatic hip OA were treated with one injection of 2 ml of hylan G-F 20 under ultrasound guidance. During the study, patients were evaluated for safety and efficacy using the Lequesne index, a visual analogue scale (VAS) measure of hip OA pain and analysis of NSAID consumption. Patients treated with hylan G-F 20 in this study showed clinically significant reductions in Lequesne and VAS scores and in the consumption of NSAIDs up to 3 months after the injection. In the 12 patients treated (total of 14 injections), no systemic adverse events were observed. Three patients reported mild, local pain post-injection. This study demonstrates the potential of ultrasound-guided intra-articular injections of a viscosupplement into the hip joint and gives positive preliminary information about the safety and efficacy of hylan G-F 20 for the treatment of symptomatic hip OA.