Smoking is a major risk factor for head and neck cancer. Smoking during diagnosis and treatment increases risks for disease recurrence, treatment failure, and increased side effects. Despite recommendations, many patients fail to stop smoking. A theory-based nurse-led intervention program was developed to support smoking cessation. This article describes the program itself and presents a framework approach for analysis of unstructured diary notes to understand the experiences of 13 patients and 2 nurses in regard to the program. The results are presented in 3 major categories: the patient-nurse relationship, factors facilitating or hindering behavioral change, and drug (ab)use. The most salient new finding of the study is the importance of a therapeutic patient-nurse relationship on the smoking cessation process, which was recognized in both patient and nurse diaries. These findings lend further support to known benefits of nurse-led interventions. The situation in Sweden, with radiation therapy given by specialist nurses, allows a unique possibility to integrate smoking cessation programs with existing cancer care. This has made it possible to determine when the patient is well-motivated for change, to balance the smoking cessation process with other care needs, and to view smoking cessation as an intrinsic part of the patient's anticancer treatment.