The beliefs of nursing professionals who care for families experiencing illness are fundamental to the quality of the nurse-family relationship and the level of the nurse's involvement in the therapeutic process of Family Systems Nursing. It is essential to have valid and reliable instruments for assessing nurses' illness beliefs, especially in the Spanish context where no instruments have been identified to date. The Iceland Health Care Practitioner Illness Beliefs Questionnaire (ICE-HCP-IBQ) is a reliable and valid measure of professionals' beliefs about their understanding of the meaning of the illness experience of families. The purpose of this study was to adapt and psychometrically test the Spanish version of the ICE-HCP-IBQ (N= 249 nurses). The exploratory factor analysis showed one-factor solution with good internal consistency (Cronbach's alpha = .91) and test-retest reliability (r= .72,p< .01). This questionnaire is a promising tool for mapping nurse's illness beliefs and monitoring the effectiveness of family nursing educational interventions in the Spanish context.