The authors of this study examined the effect of Orem's Self-Care Deficit Theory (OSCDT) based education and telephone follow-ups on the self-care agency, anxiety, loneliness, and well-being of patients with colorectal cancer chemotherapy. In this study, data of 47 patients with colorectal cancer (randomly assigned into the intervention or control group) were collected between April 2016 and March 2017 from a university hospital's daytime chemotherapy unit in Turkey. Before chemotherapy, the intervention group was given individualized education based on the OSCDT and an educational booklet. After chemotherapy treatments, these patients received a telephone follow-up call. The control group received only routine nursing care. The self-care agency and general well-being, and its sub-dimensions, of the intervention group increased, and its state-trait anxiety and loneliness levels decreased, when compared with the control group. Nurses must play a more active role in education and follow-ups, and telephone follow-ups should be included in nursing care in chemotherapy units.