Background: G-CSF is now used widely therapeutically to overcome neutropenia, a common side effect associated with chemotherapy. G-CSF is shown to improve neutrophil functions such as the phagocytosis, bactericidal and respiratory burst activity but not chemo taxis in cancer patients on chemotherapy. The varying results of various studies, raises questions about the functional competence of G-CSF induced neutrophils. Aims and Objectives: To evaluate the functions of neutrophils before G-CSF treatment and compare this with the neutrophil functions induced by G-CSF during chemotherapy. Materials and Methods: 30 patients with solid tumours coming to Oncology Department of VIMS & RC and other Oncology centres in Bangalore. And 30 healthy volunteers participated in the study. Blood samples were collected from patients G CSF administration and after G CSF administration during chemotherapy. Results: Neutrophil count was significantly improved after administration of G CSF. There was a statistically significant increase (P value<0.01*) in the killing capacity of Neutrophil after G CSF administration. Oxidative burst activity of Neutrophil showed slight improvement after G CSF therapy. Conclusion: Killing activity of the Neutrophil had improved in our study although not up to normal level. Phagocytic functions had reduced significantly in the post G CSF samples