The aime of this study is to assess the effect of a multimodal group exercise intervention, as an adjunct to conventional care, on fatigue, physical capacity, general wellbeing, physical activity, and quality of life in patients with breast cancer who were undergoing adjuvant chemotherapy. The study was conducted in Tishreen university hospital in Lattakia the participants were 164 women with breast cancer. Supervised exercise comprising high intensity cardiovascular and resistance training, relaxation and body awareness training, massage, nine hours weekly for six weeks in addition to conventional care, compared with conventional care. The intervention group showed an estimated improvement at six weeks for the primary outcome, fatigue, of −6.8 (−12.3 to −0.9), P=0.02. Significant effects were seen on vitality for physical functioning 2,5 (-0,4 to 5,2), role physical 4,5 (-1,8 to 11,1), role emotional -0,3 (-4,0 to 3,3), and mental health 1,9 (-2,5 to 6,1) scores. No significant effect was seen on global health status/quality of life. A supervised multi modal exercise intervention including high and low intensity components was feasible and could safely be used in patients with breast cancer who were receiving adjuvant chemotherapy or treatment for advanced disease. The intervention reduced fatigue and improved vitality, muscular strength, and physical and functional activity, and emotional wellbeing, but not quality of life.