Sonographic patterns of thyroid disease were correlated with pathologic findings. Twenty-eight cadaver thyroid glands were prospectively examined with a high-resolution real-time ultrasound scanner. Ultrasound findings were correlated in detail with gross and microscopic findings. Ultrasound is very accurate in detecting architectural variation, adenomatous goiter, and solitary nodules. Ultrasound cannot distinguish benign from malignant nodules, but it can be used to measure changes in nodule size. Glandular asymmetry and multiple solid nodules must be present for confident diagnosis of adenomatous goiter; hemorrhage, necrosis, and calcific spherules may be present in varying amounts. Fibrous septae, dilated follicles, and vascular calcification are found in normal aging thyroid glands. Using these criteria, ultrasonography is very accurate in the diagnosis of adenomatous goiter.