Although anomalies affecting the optic nerve head are usually clinically innocuous, they can sometimes cause significant symptoms and lead to visual loss. It is important to be able to recognize even the relatively benign lesions in order to differentiate them from other more threatening lesions or disease processes which they may clinically resemble. An awareness of the clinical appearance of disc anomalies is especially important in the differential diagnosis of optic nerve glaucomatous changes. Some anomalies cause various types of visual field loss which, if the actual disc lesion is not recognized, may lead to unnecessary neurologic evaluation or even to intracranial surgery. The optic nerve changes in acquired myopia and in the congenital tilted disc syndrome should be clearly defined and differentiated: high (pathologic) myopia may be highly progressive with many dangerous secondary sequelae, while the latter anomaly is stationary. Finally, there is a group of conditions, collectively termed "elevated anomalies of the disc," which must be considered in the differential diagnosis of papilledema and potentially dangerous intraocular tumors, particularly retinoblastoma. This review provides a clinicopathologic correlation comparing the characteristics of the normal optic disc to those of the most important congenital anomalies of the disc.