The aim was to describe the perception of energy, stress, nausea and pain after a single exercise session during chemotherapy. The project is based on self-reported data in 57 women with breast cancer who performed exercise during chemotherapy. Changes from before to immediately after a single exercise session were analysed in different time points during a course of chemotherapy. We found that energy and nausea improved immediately after an exercise session performed in first week after chemotherapy infusion. This was true for both endurance and resistance exercise. Energy level increased after an exercise session throughout the chemotherapy course, and stress was reduced at the beginning of the course. Furthermore, the energy increase was larger when the energy level before the session was lower.