Introduction Positive attitudes towards family involvement in nursing care are essential for improving the involvement of and collaboration with patients' families. The aim of this study is to explore nurses' attitudes towards the importance of families in nursing care. Method Using a cross-sectional design, hospital and homecare nurses completed the Families Importance to Nursing Care (FINC-NA) scale, Dutch language version, consisting of four subscales. Data were analysed using descriptive statistics and regression analyses. Results A total of 426 hospital and homecare nurses were eligible for analysis (mean (SD) age 42 years (13), 93% female). The mean (SD) attitude of nurses was 63.8 (12) (100-point scale) on the FINC-NA. Less than half of the nurses (44%) considered family as a collaboration partner, and 37% of nurses stated that families should be invited to actively participate in planning patient care. The nurses' attitudes were explained by years of work experience in nursing, work setting and existing policy regarding families in patient care. Conclusion This study identifies areas of improvement regarding to nurses' attitudes towards the importance of families in nursing care in order to establish a more family-focused approach in nursing care. Nursing policies should facilitate working with families as part of regular nursing processes. Furthermore, the importance of family involvement in care should be an explicit matter of concern for nursing educational institutions and for policy making within healthcare organisations.