Background: Macrolane™ is a hyaluronic gel acid for breast augmentation, claimed to be reabsorbable and biocompatible. Despite these producer’s assertions Macrolane™ may last more than 2 years after its placement, causing complications as product migration and lumps. Objective:In this study High Frequency Ultrasound (HFUS) is compared to Magnetic Resonance Imaging (MRI) in Macrolane™ complications diagnostics, with costs analysis. Complication treatment is discussed. Methods: Five female patients, aged 27 to 45, sought medical advice for non tender breast deformity and lumpiness after Macrolane™ breast enhancement performed 2 to 24 months before. All patients underwent HFUS and MRI. Results: Both techniques identified the filler’s site and quantity. HFUS has lesser costs and better patient acceptance, MRI consent better product visualization with respect with regional anatomy. Three patients required Macrolane™ removal, two refused any treatment. Conclusions: HFUS and MRI are useful diagnostic tools after Macrolane™ consenting differential diagnosis with other breast lumps. Complete surgical removal of Macrolane™ may be difficult to achieve.