Background: In serious health conditions, like childhood cancer, parent proxy reports are used for obtaining information. Previous studies have shown controversial results on agreement between children’s and parents’ ratings. In addition, there is lack of proxy studies in research including young children. The aim of the present thesis is (a) to examine how young children as self-raters and mothers as proxy-raters report over time on cancer related health issues, and (b) to explore the factors that may affect the agreement of each mother-child pair.

Method: A longitudinal quantitative research design was chosen. Eight young children with cancer aged three to six years and their mothers were followed with questionnaires every six months for four time points. One measure on children’s feelings about their health situation and one measure on perceptions of their everyday functioning were completed by children and mothers at each time point. Descriptive statistics were used for data analysis.

Results: Higher frequency of agreement was found in T4 (18 months after the diagnosis) for both measures. Between the two measures, higher frequency of agreement was found for the functioning measure. The mother’s educational level was found to be correlated with higher frequency of agreement (functioning measure).

Conclusion: The time progress, the mother’s educational level, the number of siblings, the specific shared experience, like preschool, and the concrete and observable issues, like “functioning” rather than “feelings”, were found to be correlated with higher frequency of agreement between young children with cancer and their mothers. The convenient and small sample imposes the need for further research.