Background. Caregivers are often involved in and affected by the patient's disease. The questionnaire 'Cancer Caregiving Tasks, Consequences and Needs Questionnaire' (CaTCoN) was developed to measure caregivers' experiences. The aim of this study is to evaluate the construct validity and reliability of the multi-item scales in the CaTCoN using psychometric analyses as well as tests of convergent and discriminant validity with the existing instruments FAMCARE and Family Inventory of Needs (FIN). Material and methods. Based on theoretical considerations, a subscale structure in the CaTCoN was hypothesized, and the subscales were tested by item-item correlations, followed by factor analysis, calculation of internal consistency by Cronbach's alpha, and multitrait-scaling analysis. Further, theoretically based hypotheses about convergence and divergence between CaTCoN and FAMCARE/FIN (sub)scales were formulated and tested. Results. Analyses were based on 590 caregivers' responses. Initially, 11 CaTCoN subscales were hypothesized. The item-item correlations and factor analysis lead to some revisions, but the analyses confirmed the hypothesized subscales to a large extent, resulting in nine CaTCoN subscales (Cronbach's alpha range 0.65-0.95). The hypothesized convergent CaTCoN and FAMCARE/FIN subscales correlated 0.59-0.74, and hypothesized divergent CaTCoN and FAMCARE/FIN subscales correlated -0.11-0.25, thus confirming the hypotheses concerning convergent and discriminant validity between CaTCoN and the existing questionnaires FAMCARE and FIN. Conclusion. Taken together the psychometric analyses and tests of convergent and discriminant validity indicate that the validity and reliability of the CaTCoN are satisfactory.