Cleft lip and palate or orofacial cleft (OFC) is one of the most common congenital malformations. The average incidence is around 1 every 1 000 live births. Different types of cleft lip and palate exist: cleft lip (CL), cleft lip and alveolus (CLA), cleft lip, alveolus and palate (CLP), and cleft palate only (CPO). Genetic studies on human samples have demonstrated that OFC has a heterogeneous genetic background and environmental factors also contribute to disclose this malformation. Because of the complex aetiology of OFC, studies on different and homogeneous populations can be useful in detecting environmental and genetic factors involved in the onset of this disease. The aim of the present study is to evaluate the relation between gender, type of cleft and affected side in a group of patients in Southern Italy.Six hundred and fifty patients were enrolled in this retrospective study. They were operated at the Dental Clinic of the Second University of Naples in the period 1980-2002. Gender, type of cleft and affected side were analysed by means of the "Test for comparing two proportions".Among the analysed variables it was statistically demonstrated that overall CLP is more frequent in males as well as bilateral CLP whereas overall CPO is more frequent in females as well as right microform of CL.The identification of gender related subtypes of cleft is in accordance with data reported in similar studies on different populations and confirms that OFC is an heterogeneous disease even in a homogeneous ethnic group.