Abnormalities of the Achilles tendon and adjacent bursae are common problems that may be difficult to diagnose clinically. Twenty patients with symptoms involving the Achilles tendon and 10 control subjects were evaluated with real-time sonography in order to explore the role of sonography in defining abnormalities of the tendon and adjacent bursae and in differentiating between conditions requiring surgery and those needing conservative therapy. Normal anatomic structures seen consistently included the Achilles tendon, the musculotendinous junction, the retrocalcaneal bursa, and the calcaneal tendon insertion site. The normal range of tendon thickness was 4-9 mm (mean, 6.2 mm). All patients had repeat sonograms after either clinical resolution (14 cases) or surgical intervention (six cases). Twelve of the symptomatic patients had abnormal findings. Partial ruptures of the Achilles tendon were reliably differentiated from other lesions. No evidence of tendon thickening was found in tendinitis. Tendon thickening was found only in cases of previous tendon rupture. The superficial tendo Achillis bursa was imaged only when inflamed. Sonography was found to differentiate reliably between conditions that require surgical intervention and those that will respond to conservative therapy.