During dental treatment children are usually under psychological pressure. With the Sarnat Behaviour Score five different types of patients can be distinguished. There is no method that measures the impact of dental atmosphere and dentist's behaviour on the young patients' readiness to cooperate. The objective of the present study was the implementation and evaluation of a questionnaire on this subject. Eighty-eight patients participated in this study. In the first part of the new questionnaire personal information was collected. The second part consists of 43 items and investigates the relationship between dentist and patient and reflects the atmosphere of the environment. Statistical analysis was performed using the Chi-square test. There were statistically significant differences between the cooperative and non-cooperative group, as regards the perceived honesty of the dentist, the ability to explain and wish to help. Uncooperative children are significantly more often afraid of the dental environment. Sympathy alone has only a minor effect on children's cooperation. Children should be treated with empathy. Especially younger patients appreciate detailed explanations by the dentist. Children's non-cooperative behaviour results often from their aroused interest in the unknown environment, which causes an unpleasant perception of the whole setting.