Costal cartilages of 10 controls and 12 patients with Tietze's syndrome (n = 6), deformed (exaggerated bowing) cartilage (n = 4), focal enlargement (n = 1), and cancer-invaded cartilage (n = 1) were examined with ultrasonography. In controls, ultrasonography detected 237 of 240 costal cartilages (98.8%) and 58 of 105 intercartilage connections (55%) with three variations. Correlation with CT was available in 7 patients (1 Tietze's syndrome, 4 deformities, 1 cartilage enlargement, and 1 cancer) among 8 patients whose CT results were known to the sonographer. Sonography showed normal (n = 4) or marginally blurred (n = 2) cartilages in 6 Tietze's syndromes. Ultrasonography is a promising technique in the examination of costal cartilages.