The purpose of this prospective longitudinal study was to describe the occurrence, severity, and pattern of symptoms experienced by women during and after primary radiation therapy for breast cancer. A convenience sample of 30 women was recruited from a community hospital. The Symptom Profile by King et al (Oncology Nursing Forum. 1985;12(4):55–61) was adapted to measure 11 symptoms, and the Profile of Mood States assessed psychological status. Data were collected weekly during radiation and monthly for 3 months after treatment. There was a pattern of increasing incidence during treatment for the most commonly reported symptoms: fatigue (33%–93%), skin changes (36%–100%), sensation changes (28%–79%), and breast swelling (11%–38%), with gradual improvement over the following 3 months. Sleep problems were reported by nearly half of the subjects during and after treatment. Severity ratings of symptoms were mild to moderate but significantly higher by the end of therapy (P ≤ .01). There were no significant differences in psychological mood states during or after treatment except for the fatigue subscale (P ≤ .05). These findings will assist the nurse in preparing women for predictable symptoms during and after a course of breast irradiation and direct assessment, and provide data to support evidence-based interventions to minimize symptom distress.