There is a growing demand for complementary and alternative medicines (CAMs) among people with cancer. This study aims to describe how nurses’ respond to people with cancer who use CAMs, and the factors which might contribute to these different responses. A grounded theory approach was used. Six semistructured interviews were conducted with nurses who were working in cancer settings. The core category which emerged from this study was ‘nurses’ responses towards patients who use CAMs’. Nurses respond in a variety of ways to patients who use CAMs. They include: open, sceptical and ambivalent responses. A range of factors which influence the way nurses respond were also identified. These include the ambiguous definitions of CAM, nurses’ personal philosophies, life experiences, evidence of the therapy’s effectiveness, impact on patients, the motives of patients who use CAM and organizational culture. Several implications for nursing education and practice are identified from these findings.