The study is based on a longitudinal cephalometric follow-up of X-ray films of patients with a complete unilateral cleft lip and palate during puberty. Carthesian x, y coordinates of the total of 22 landmarks on the lateral films of 25 patients with the same diagnosis and therapy were established, which served as outcome data for shape analysis. The changes in facial shape experienced by patients between their 10th and 15th year were evaluated by the thin-plate splines (TPS) method. We used the TPS method to find a function which transforms the shape of the face at the age of 10 as well as the square TPS grid into the facial shape at the age of 15 years with the deformed TPS grid. With the help of Geometric PCA for Bookstein's coordinates we found individuals with different shapes who develop abnormally during puberty and whose development is not well predictable. During puberty the face becomes relatively elongated. The most pronounced deformation is caused by the shift of the first permanent molar anteriorly, or a relative shortening of the frontal part of the dental arch. In the anterior direction the position of landmarks changed only in the area of nose; the alveolar process shows retrusion. The position of the mandible in relation to the maxilla change mainly in the inferior direction; the mandibular angle shifts posteriorly. The shape of skeletal profile was compared with a group of patients with the same diagnosis who underwent different therapy.