PURPOSE: The efficacy of physical exercise prescription as therapy in breast cancer survivors is largely documented in literature. Unsupervised exercise produces short- term improvements in physical fitness of breast cancer survivors, but regarding the mid-term effectiveness only few studies are available. The purpose of this study was to assess the effects of an unsupervised exercise prescription program on body composition, physical fitness and Health Related Quality of Life of breast cancer survivors. METHODS: Forty-two (average age 52.0±10.1 years) women were enrolled. Assessments performed at baseline and after 6 months of exercise prescription: - body composition (anthropometric parameters and bioimpedance analysis); - physical fitness: aerobic capacity by Six-Minute Walk Test (6 MWT), limbs strength by Hand Grip Test and Chair Stand Test, flexibility by Sit and Reach Test; TOGLIERE PRESSIONI - Health Related Quality of Life (SF-36). Statistical analysis was conducted by Student’s t-tests and multiple regression. RESULTS: Body composition improvements: - BMI (T0=27.3±4.2; T5=26.1±3.9 kg/m2; p<0,001); - waist circumference (T0=90.2±10.8; T5=85.3±9.8 cm; p<0,001); - extracellular water (T0=17.5±1.9; T5=16.8±1.9 L; p<0,01); - fat mass (T0=25.0±8.1; T5=22.6±7.2 kg; p<0,001). Physical fitness improvements: - 6 MWT (T0=518.6±133.0; T5=584.8±97.2 m; p<0,001); - Hand Grip (T0=24.3±4.8; T5=26.5±4.5 kg; p<0,01); - Chair Test (T0=14.5±3.8; T5=18.3±4.3 repetitions; p<0,001); - Sit and Reach (T0=2.6±9.3; T5=8.5±7.1 cm; p<0,001). Health Related Quality of Life improvements: - Physical Functioning (T0=72.7±24.6; T5=83.7±17.1 %; p<0,001); - General Health (T0=64.7±20.4; T5=69.1±18.9%; p<0,001); - Social Functioning (T0=60.5±24.5; T5=67.6±22.9%; p<0,05); - Mental Health (T0=63.4±14.8; T5=67.3±12.5%; p<0,05). The percentage change in fat mass has been associated with adjuvant cancer therapy (intercept= -0,016; b=8,629; p<0,05). CONCLUSIONS: An unsupervised exercise prescription program improves body composition, physical fitness and Health Related Quality of Life in breast cancer survivors. Longer term follow-up studies to establish the real capacity of this program to induce long-term changes in lifestyle are needed.