In order to find the distribution, causes and treatments of cleft lip and/or palate, I analyzed 113 patients of cleft lip and/or palate who were treated in the Department of Oral and Maxillofacial Surgery, School of Dentistry, Wonkwang University, Iksan, Chunbuk, KOREA from September 1984 to August 1995. The obtained results were as follows. 1. In total 113 patients of cleft lip and/or palate, male patients were 63 cases (56%) and female patients were 50 cases (44%). 2. In distribution of cleft lip and/or palate, cleft lip patients were 30 cases (27%), cleft palate patient were 23 cases (20%) and cleft lip and palate patients were 60 cases (53%). 3. Unilateral cleft lip patients (78 cases: 87%) were larger than bilateral cleft lip. In unilateral cleft lip patients, lip side cleft lip patients (45 cases: 50%) were larger than right side cleft lip patients (33 cases: 37%). 4. Possible causes of cleft lip and/or palate were related with familial tendency, drug intoxication, malnutrition, old maternal age, stress and hypoxia during 4-8 weeks of pregnancy period. 5. The favorite treated method of cleft lip was Millard rotation-advancement method. Probably the most popular operated period was 3 months. 6. The useful operating technique of cleft palate was Wardill V-Y flap method. The most popular period has been 18 to 24 months. 7. In 11 patients with velopharyngeal insufficiency, hypernasality decreased by superior based pharyngeal flap pharyngoplasty. 8. Cleft alveolus was treated with autogenous and allogeneic bone graft. The most appropriate operation period was 9 to 11 years.