OBJECTIVE: To determine the efficacy of IA corticosteroid (CS) injection in pain reduction for hip OA under ultrasound (US) guidance. METHODS: Forty patients [mean age 62.78 (8.16) years] fulfilling ACR criteria for hip OA, with synovitis detected at US, gave their consent for IA US-guided CS injection because of pain refractory to conventional therapy. At baseline, at 1 and 3 months, patients filled up a visual analogue scale (VAS) pain on walking, performed the Lequesne index and were checked by US for synovitis. Results were compared with age-matched controls. The occurrence of side effects both short and long term was monitored. RESULTS: IA steroid deposition was performed under US guidance. After 1 and 3 months, walking pain VAS was significantly reduced vs baseline (P < 0.001) and had high correlation with Lequesne index. Synovial hypertrophy was reduced in 75% of the hips after 1 and 3 months vs baseline (P < 0.001). In the group of controls, hip walking pain VAS, Lequesne index and synovial hypertrophy were not changed at 3 months vs baseline (P > 0.05). Transient facial rash was present in 16 patients during the first 24-48 h after injection. No side effects were reported. CONCLUSION: US-guided steroid injections in hip OA is an efficacious and safe therapeutic approach to achieve pain control and reduction of synovial hypertrophy avoiding the use of X-ray-guided procedure.