Introduction & Objective: Quality of life is a subjective and multi dimensional concept assessing physical ,social ,psychological and role function domains  .cancer diagnosis and its therapy have a negative impact on quality of life .one type of cancer  treatment is chemotherapy that administered to destroy cancer cells .the studies show that cancer treatment with  side effect and toxicity that diminish  quality of life. The purpose of this study was determine changes of quality of life  in cancer patients before and after 3 cycle chemotherapy in selected hospitals of Tehran and shahid  beheshty medical science university in 1380-81.

Materials & Methods: This is a descriptive –correlative study that utilized a purposeful sampling .one hundred twenty one out patients with cancer participated in this study data was collected by interview .the instruments used included: the sample selection and demographic data form, social support questionnaire, fatigue severity scale, piper fatigue scale and quality o life scale.

Results: The finding of t-  test  indicated  that a significant different between mean of quality of life(P<0.001) before and after 3 cycle chemotherapy .significant different  was found between means of physical function (p<0.003) role function(p<0.001), psychological (p=0.006) domains  before and after 3 cycle chemotherapy, but significant  different  was not found between cognitive  and social domains before and after 3 cycle chemotherapy.

Conclusion: Quality of life negatively affected during chemotherapy. The nurses by appropriate intervention and patient's education about self care intervention can help to reduce fatigue and side effects of chemotherapy and improve quality of life.