Personal health-related resources are essential for women with breast cancer, as these help them to maintain their own health and well-being during cancer care. Nurses play an important role in providing support to identify personal health-related resources of women during cancer treatments.

To develop and test the psychometric properties of a new self-assessment personal health-related resources (PHRR) instrument for working-age women receiving breast cancer care.

A four-phase instrument development process was used. The data were analysed using the content validity index, content validity ratio and exploratory factor analysis. Reliability was tested using Cronbach's α coefficients.

The instrument’s content validity index was 0.93. Exploratory factor analysis showed that the instrument version 3.0 comprised three main factors, 12 sub-factors and 46 items, which explained 67.4 % of the total variance in the measured variable. The instrument’s internal consistency was high, with Cronbach’s α of 0.92.

The instrument showed acceptable psychometric properties and was suitable for measuring PHRR in women aged 18–65 years with breast cancer. The instrument provides multidimensional understanding of the PHRR of women with breast cancer. The PHRR instrument can be used to achieve a comprehensive understanding of the personal health-related resources for women with breast cancer during cancer care. This instrument can provide information how to support women and development psychosocial support in different phases of illness.