OBJECTIVES: To analyze gender differences in cleft pattern by the clinical statistical study of Japanese patients with cleft lip and/or cleft palate. STUDY DESIGN: Cleft pattern modeling was used to analyze 782 patients with cleft lip and/or cleft palate (417 males and 365 females) who had been examined at the Cleft Lip and Palate Center, Aichi-Gakuin University Hospital, and whose details could be confirmed. Relationships between gender and cleft type were analyzed with chi-squared test. RESULTS: A comparison of gender differences by cleft type revealed that a greater percentage of males had milder cleft lip, cleft lip and palate, or cleft palate, whereas the percentage of females tended to be greater as cleft severity increased. CONCLUSIONS: Modeling of cleft patterns enables more detailed classification of cleft lip and palate, and can lead to a greater understanding of pathology.