Objectives: Complementary and alternative medicine (CAM) use is prevalent, but specific use of CAM across cancer treatment is underinvestigated. The objectives of this study were to assess changes in CAM use across cancer treatment; specific reasons for and satisfaction with specific types of CAM used; and associations of CAM use with stress, mood, and quality of life (QOL) in women with newly diagnosed breast cancer. Design and setting: Seventy-seven women with early-stage breast cancer who underwent active cancer treatment participated in the study. Data were collected three times: shortly after cancer diagnosis and 2 months and 6 months after the start of adjuvant cancer therapy. Outcome measures: CAM Questionnaire, Impact of Event Scale (stress), Profile of Mood State (mood), and Functional Assessment of Cancer Therapy-Breast Cancer (QOL). Results: Mean age was 52.4 years, and 94%-97% of women used on average five to six CAMs across three time points. Women largely started CAM use before cancer diagnosis and continued across cancer treatment. The five most common CAMs were prayer (88.3%), multivitamin use, massage, and vitamins E and C, followed by music, meditation, green tea, chiropractic care, and vitamin A, with little changes in types of CAM use across cancer treatment. Satisfaction was high, and satisfaction with prayer was the highest. Prayer, meditation, and music were used specifically for a feeling of control, whereas vitamins were used to improve the immune system, showing clear patterns. Stress, mood disturbance, and QOL declined significantly over time, p < 0.001-0.04, but the number of CAMs used was unrelated to these variables. Conclusions: CAM use was highly prevalent with multiple CAMs and continued throughout cancer treatment. Prayer was the most common CAM; it had the highest satisfaction rating and the perception of being most helpful. The effect of long-term CAM use requires further investigation on psychological and biobehavioral outcomes with consideration of demographic and clinical characteristics.