Background. The aim of this prospective study was to assess the effectiveness of a single ultrasound-guided steroids injection in the treatment of Morton's neuromas and whether the response to injection correlates with the size of neuroma. Methods. Forty three patients with clinical features of Morton's neuroma underwent ultrasound scan assessment. Once the lesion was confirmed in the relevant web space, a single corticosteroids injection was given using 40 mg Methylprednisolone along with 1% Lidocaine. All scans and injections were performed by a single musculoskeletal radiologist. Patients were divided into two groups based on the size of the lesion measured on the scan. Group 1 included patients with neuromas of 5mm or less and Group 2 patients had neuromas larger than 5mm. The Visual Analogue Scale (Scale:0 to 10), the American Orthopaedic Foot and Ankle Society score (AOFAS) and the Johnson satisfaction scale were used to assess patients prior to injection and then at 6 weeks, 6 months and 12 months following the injection. Results. Thirty nine patients had confirmed neuromas. Group 1 (lesion ≤5mm) included 17 patients (mean age, 30 years) (7 males, 10 females) and Group 2 (lesion >5mm) had 22 patients (mean age, 33 years) (8 males, 14 females). VAS scores, AOFAS scores and Johnson scale improved significantly in both groups at 6 weeks (p < 0.0001). At 6 months post-injection, this improvement remained significant only in group 1 with regards to all scores (p < 0.001). At 12 months, there was no difference between both groups and outcome scores nearly approached pre-injection scores. The need for surgical treatment for persistent symptoms was similar in both groups (p = 0.6). Conclusion. A single ultrasound-guided corticosteroids injection offers generally a short-term pain relief for symptomatic Morton's neuromas. The effectiveness of the injection is likely to be more significant and long-lasting for lesions smaller than 5mm