After briefly review facial morphogenesis, the authors define facial clefts, distinguishing primary clefts, secondary clefts, and residual clefts. They discuss the uncertainties surrounding the embryology and clinical features of palpebral colobomas. The various pathogenetic concepts are analysed: amniotic hypothesis, vascular hypothesis, fusion defect. The various classifications of rare facial clefts are reviewed, with particular emphasis on Tessier's classification and the so-called Milan classification. The general principles of surgical treatment are described together with the various skeletal and soft tissues procedures.