The purpose of the study was to examine the effects of a supervised high- and low-intensity structured training program in cancer patients concurrently undergoing chemotherapy. Seventy patients, in different stages of the disease and with different diagnoses (48 females, 22 males), between 18 and 65 years of age (mean age 42.8) participated in a 9-h weekly training program over 6 weeks. The intervention involved physical exercise, relaxation, massage, and body-awareness training. Physical capacity (one-repetition maximum tests (1RM), VO2max) and body composition (weight, skin-fold) were compared before and after the exercise intervention. The average increase in muscular strength was 41.3% (P<0.001) and 14.5% in aerobic fitness (pre: 2.27+/-0.597 L/min, post: 2.56+/-0.644 L/min, (P<0.001). The exercise intervention significantly increased the weight of the subjects by 1% (pre: 72.62+/-13.42 kg, post: 73.25+/-13.44 kg, P=0.016). There was a significant decrease in skin-fold measurements by 3% (P=0.031). The exercise intervention was well tolerated, provided that daily screening criteria were adhered to. The effects of resistance and cardiovascular training observed in this short-term study support the theory that exercise is a beneficial intervention strategy for increasing muscle strength and aerobic fitness during antineoplastic chemotherapy. This type of exercise program can be an important component of complementary treatment for cancer patients undergoing chemotherapy.