As Magnetic Resonance (MR) imaging and Ultrasound (US) allow the evaluation of soft-tissue structures not previously possible with other imaging techniques, a clinical study has been undertaken to determine the value of these two modalities in the detection of lesions in the Achilles tendon (AT), other than acute total rupture. Seven healthy subjects and 28 symptomatic patients with Achillodynia and/or signs of thickening of the AT were investigated with MR and US; all results were compared with the clinical features. Surgical findings were available in 14 patients. The patients were divided into three groups; those with tendon thickening, incomplete and complete chronic ruptures. Thickening of the AT was easily detected with both methods. MR was superior in the detection of incomplete tendon rupture and in the evaluation of various stages of chronic degenerative changes. We conclude that only if US remains unclear, an additional MR study should be performed and together with the clinical diagnosis indication for surgery can be made more efficient.