Objective: To study criteria for helping to select children with special needs for dental treatment under general anaesthesia. Materials and methods: Group of 30 children (aged under 18) examined on the Course at the Universidad Complutense de Madrid (UCM) (Specialisation on holistic dental treatment of children with special needs) and subsequently referred to the Disabled Children?s Oral Health Unit (DCOHU) within Primary Health Care Area 2 of the Madrid Health Service (SERMAS) where dental treatment under general anaesthesia was given during 2005. Relevant data were taken from their case histories with regard to their general health, oral health and behaviour. Results: In most of the children (22 children), it was possible to carry out a complete dental diagnosis. With regard to medical diagnoses, the most frequent pathology was cerebral palsy (8 children), but it was not possible to establish a link between the pathology and the use of general anaesthesia. With regard to oral health, most of the children received restorative treatment in all 4 quadrants (26 children). On the basis of scales for behavioural evaluation and movement, most of the children (17 children) showed clearly negative behaviour, with movements that interrupted or hindered examination. Conclusions: With the exception of certain specific medical problems, the reasons for using general anaesthesia for dental treatment in children with special needs are extensive treatment needs and bad behaviour, both of which can be judged objectively.