A temporal bone histopathological study was conducted to detect temporal bone anomalies in 20 ears (10 cases) of individuals with congenital heart anomalies. We restricted our study to patients more than one year of age, and to heart anomalies of unknown etiology. The temporal bones were obtained from refrigerated cadavers, fixed in formalin, embedded in celloidin, cut in a horizontal plane, stained with H & E, and mounted on glass slides for light microscopic study. Anomalies observed in the middle ear were: remnants of mesenchymal tissue (8 ears), wide angle of the facial genu (6 ears), persistence of the stapedial artery (5 ears), large defect of the facial canal (4 ears), high jugular bulb (4 ears), and bulky incus (2 ears). Inner ear anomalies consisted of a shortened cochlea (5 ears), anomaly of the horizontal canal (3 ears), anomaly of the posterior canal (2 ears), obliteration of the cochlear aqueduct (2 ears), and patent utriculoendolymphatic valve (1 ear). Most of the anomalies observed appeared to be due to arrested development, and resembled features which may be found at various stages of fetal life. Structural anomalies were more commonly found in the mesoderm than in the ectoderm, and middle ear anomalies were more frequently encountered than anomalies of the inner ear. No definite relationship between these anomalies observed in the temporal bone and hearing problems which had been recorded clinically for these patients could be detected. However, the large defect (more than one third of the circumference) of the facial canal, the high jugular bulb, and the stapedial artery persistence should be recognized as problems since they may be encountered during middle ear surgery.