Aim and introduction: Cancer patients undergoing radiotherapy need to adhere to complex self-care instructions to maintain overall health and manage local and systemic side effects. Patients frequently face challenges in recalling and effectively implementing these instructions, potentially affecting their self-efficacy and treatment outcomes. The teach-back method, an interactive technique in which patients are asked to repeat the instructions provided, has been shown to enhance understanding and retention. The aim was to assess effect of teach-back on recall of instructions and self-efficacy. Materials and methods: A posttest-only comparison group design was employed. Research settings were the oncology and radiotherapy outpatient department, in New Delhi. A total of 72 participants who were going to receive radiotherapy for the first time were randomly allocated (36 each) to experimental and control groups. Outcome variables included recall of instructions and self-efficacy which were assessed using recall checklist and self-efficacy rating scale. The assessment for the recall was done on day 1 and for self-efficacy on day 5. Results: Both groups were homogeneous in terms of recall of instructions and self-efficacy. In the experimental group, 94.7% had good recall and 5.3% had average recall, while in the comparison group 47.1% had good recall, 50% had average recall, and 2.9% had poor recall. In the experimental group, 94.4% had high self-efficacy, and 5.6% had average self-efficacy. In comparison group 69.4% had high self-efficacy and 30.6% had average self-efficacy. No correlation was found between recall of instruction and self-efficacy. Conclusion and clinical significance: “Teach-back” significantly improves the recall of instructions and self-efficacy. It can be used by healthcare providers in hospital and community settings.