Objectives IV The purpose of this PhD thesis was to establish the opinion of children and their parents about: a) the level of provided information in health care system, sources of information and understanding of information obtained; b) who decide about children’s health; c) the age of assent; d) if demographic data, illness of child, sources of information and decision explain their opinion towards communication, children’s decision and better information of children. Participants and methods Two groups of participants were involved in this study, children and their parents, in total 1602. The number of children were 1045 (68,4% of girls, 31,6 of boys) and 557 of parents. Average age of children was 16,18 years. Participants were examined in schools (930 children and 336 parents) and hospitals (115 children and 184 parents) in cities of Pula, Rijeka, Crikvenica, Zagreb, Osijek and Knin. Based on pilot investigation and literature search about the questionnaires related to informed assent and parents consent, a questionnaire for children and parents was drawn up. The questioner had two parts. Demographic data, data about children’s illness and hospitalization, received information and understanding of this information, informed assent and children’s’ decision making were collected in the first part of the questionnaire. The second part of the questionnaire was consists of 28 claims. Factor analysis on common factors was conducted with Oblimin rotation with the purpose of evaluation of 28 claims factor structure, separately for the sample of parents and for the sample of children. Three subscales were included in further analysis with satisfactory metric characteristics (Communication with children, Children’s’ decision and Level of children’s’ information). For the parents, one subscale was included in further analysis (childrens inclusion in decision making). V Results Information about childrens health. More than 50% of children were well informed about their illness. According to the opinion of children and parents, parents were most common source of information. According to the childrens opinion, physicians (8.68%) and other health givers (3.99%) significantly contribute to the understanding of information in comparison to the parents (0.03%). Children with severe diagnose were better informed and better understood received information. The same children were better informed by parents and other health care givers in comparison to the doctors and internet. Boys participants hospitalized during investigation had greater need for information in comparison to the girls. Decision about children health. According to children opinion, physicians and parents made decisions most frequently. According to the opinion of parents, parents made decision most frequently. Boys and parents thought that children should be more frequently involved in decisions making. The age of assent and participation in decision making. According to the opinion of most children, the age of consent is 16 years. According to the opinion of parents the average age for receiving information is 15 years and for the consent is 18 years. Hierarchic regression analysis of children answers determinate four group of predictors (demographic data, illness, source of information and source of decision making) explain 49% of variance Communication with children, 25% of variance Children decision making and 41% o Children information. According to the parents opinion, same four groups of predictors explain totally 21% of variability of Childrens’ participating in decision making. Conclusions Information provision about illness is important to parents and children. If the children are better informed, they can understand the information properly and they will be more involve VI in decision making. The children should be informed by the experts. There are many other factors that can be connected with childrens’ information, such as gender and severity of disease. The children want to participate in decision making at the age of 16. According to parents opinion, the age of children for participation in decision making is 18 years. Our results suggest that both parents and childrens’ need more information and better communication. We can conclude that physicians and other health care providers as well as parents should be better informed about rights of children and parents.