Background: Cancer is a major public health problem that gives an economical burden on the patient and government. The incidence of different types of cell tumors are increasing nowadays. Aim of Study: To investigate the effect of inspiratory muscles training on functional capacity for patients on chemotherapy. Material and Methods: Forty male patients on chemotherapy from at least one cycle and their mean ages 37.1 ± 4.89 years. The patients were selected from National Cancer Institute, Cairo (inpatient ward). The study lasted from March 2018 to June 2018. Patients were randomly assigned into two groups. Group A (30 patients) who received inspiratory muscles training for 4 successive weeks, 5 sessions/week; and Group B (10 patients) acted as a control group on chemotherapy only. Data obtained from both groups regarding forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC ratio and 2min walk test were statistically analyzed and compared. Results: After 4 weeks of management for both groups the results showed that in FVC in the study group a significant increase by 33.44% while in control group, a significant decrease by 37.3%. FVE1 increased by 34.52% in the study group while it decreased by 34.09% in the control group. However, it was shown that no significant difference in the FEV 1/FVC ratio. Also results related to 2min walk test distance showed increase by 17.29% in group A while decrease by 15.48% in group B. Conclusion: It can be concluded that inspiratory muscles training can be adjunctive to the rehabilitation program for patients on chemotherapy aiming for enhancing their functional capacity.