Background: Clinical decision-making (CDM) is a complex nursing process undertaken by Registered Nurses (RNs) in clinical practice and a crucial component to ensure high-quality patient care. CDM is essential in planning and delivering evidenced based care to patients with constipation. Constipation is a multifactorial and subjectively distressing symptom experienced by cancer patients at various stages of their disease and treatment journey. Method: This descriptive, qualitative study explored what influenced RNs’ CDM when managing constipation in cancer patients. Purposive sampling was used to recruit six community-based RNs and five RNs from an acute medical oncology ward. Semi-structured interviews (n=11) using open-ended questions informed by the literature were conducted. Thematic analysis was used to analyse the data. Findings: Two major themes emerged: “Factors influencing practice” and “Developing partnerships”. RNs’ clinical decisions are influenced by their previous clinical and personal experiences; the reluctance to use constipation assessment tools in practice; their previous exposure to patients with cancer who have had constipation; partnerships formed, with patients and families or other RNs; and conferring with experts. Previous successes and failures to resolve constipation informs RNs’ decision-making, rather than specific knowledge, education, or using assessment tools related to constipation. Implications: The study findings span two distinct clinical settings, which provide insights and contribute to the body of knowledge about CDM. Education programs are needed to focus on educational frameworks, which foster the development of clinical knowledge that enhances CDM processes. Providing education and mentoring to nurses prior to their placement into cancer nursing specialised clinical settings may lessen the burden associated with a lack of CDM skills. An understanding of novice RNs’ CDM during their first year of practice will enable nursing managers, educators, and other health professionals to give them support and promote evidence-based practice. Education regarding knowledge and use of standardised evidenced- based constipation assessment tools are needed to assist RNs in the identification, prioritisation, and management of concurrent constipation symptoms experienced by cancer patients